repo stringlengths 7 90 | file_url stringlengths 81 315 | file_path stringlengths 4 228 | content stringlengths 0 32.8k | language stringclasses 1 value | license stringclasses 7 values | commit_sha stringlengths 40 40 | retrieved_at stringdate 2026-01-04 14:38:15 2026-01-05 02:33:18 | truncated bool 2 classes |
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TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/elgamal_key_generator.py | ciphers/elgamal_key_generator.py | import os
import random
import sys
from . import cryptomath_module as cryptomath
from . import rabin_miller
min_primitive_root = 3
# I have written my code naively same as definition of primitive root
# however every time I run this program, memory exceeded...
# so I used 4.80 Algorithm in
# Handbook of Applied Cryptography(CRC Press, ISBN : 0-8493-8523-7, October 1996)
# and it seems to run nicely!
def primitive_root(p_val: int) -> int:
print("Generating primitive root of p")
while True:
g = random.randrange(3, p_val)
if pow(g, 2, p_val) == 1:
continue
if pow(g, p_val, p_val) == 1:
continue
return g
def generate_key(key_size: int) -> tuple[tuple[int, int, int, int], tuple[int, int]]:
print("Generating prime p...")
p = rabin_miller.generate_large_prime(key_size) # select large prime number.
e_1 = primitive_root(p) # one primitive root on modulo p.
d = random.randrange(3, p) # private_key -> have to be greater than 2 for safety.
e_2 = cryptomath.find_mod_inverse(pow(e_1, d, p), p)
public_key = (key_size, e_1, e_2, p)
private_key = (key_size, d)
return public_key, private_key
def make_key_files(name: str, key_size: int) -> None:
if os.path.exists(f"{name}_pubkey.txt") or os.path.exists(f"{name}_privkey.txt"):
print("\nWARNING:")
print(
f'"{name}_pubkey.txt" or "{name}_privkey.txt" already exists. \n'
"Use a different name or delete these files and re-run this program."
)
sys.exit()
public_key, private_key = generate_key(key_size)
print(f"\nWriting public key to file {name}_pubkey.txt...")
with open(f"{name}_pubkey.txt", "w") as fo:
fo.write(f"{public_key[0]},{public_key[1]},{public_key[2]},{public_key[3]}")
print(f"Writing private key to file {name}_privkey.txt...")
with open(f"{name}_privkey.txt", "w") as fo:
fo.write(f"{private_key[0]},{private_key[1]}")
def main() -> None:
print("Making key files...")
make_key_files("elgamal", 2048)
print("Key files generation successful")
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/enigma_machine2.py | ciphers/enigma_machine2.py | """
| Wikipedia: https://en.wikipedia.org/wiki/Enigma_machine
| Video explanation: https://youtu.be/QwQVMqfoB2E
| Also check out Numberphile's and Computerphile's videos on this topic
This module contains function ``enigma`` which emulates
the famous Enigma machine from WWII.
Module includes:
- ``enigma`` function
- showcase of function usage
- ``9`` randomly generated rotors
- reflector (aka static rotor)
- original alphabet
Created by TrapinchO
"""
from __future__ import annotations
RotorPositionT = tuple[int, int, int]
RotorSelectionT = tuple[str, str, str]
# used alphabet --------------------------
# from string.ascii_uppercase
abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
# -------------------------- default selection --------------------------
# rotors --------------------------
rotor1 = "EGZWVONAHDCLFQMSIPJBYUKXTR"
rotor2 = "FOBHMDKEXQNRAULPGSJVTYICZW"
rotor3 = "ZJXESIUQLHAVRMDOYGTNFWPBKC"
# reflector --------------------------
reflector = {
"A": "N",
"N": "A",
"B": "O",
"O": "B",
"C": "P",
"P": "C",
"D": "Q",
"Q": "D",
"E": "R",
"R": "E",
"F": "S",
"S": "F",
"G": "T",
"T": "G",
"H": "U",
"U": "H",
"I": "V",
"V": "I",
"J": "W",
"W": "J",
"K": "X",
"X": "K",
"L": "Y",
"Y": "L",
"M": "Z",
"Z": "M",
}
# -------------------------- extra rotors --------------------------
rotor4 = "RMDJXFUWGISLHVTCQNKYPBEZOA"
rotor5 = "SGLCPQWZHKXAREONTFBVIYJUDM"
rotor6 = "HVSICLTYKQUBXDWAJZOMFGPREN"
rotor7 = "RZWQHFMVDBKICJLNTUXAGYPSOE"
rotor8 = "LFKIJODBEGAMQPXVUHYSTCZRWN"
rotor9 = "KOAEGVDHXPQZMLFTYWJNBRCIUS"
def _validator(
rotpos: RotorPositionT, rotsel: RotorSelectionT, pb: str
) -> tuple[RotorPositionT, RotorSelectionT, dict[str, str]]:
"""
Checks if the values can be used for the ``enigma`` function
>>> _validator((1,1,1), (rotor1, rotor2, rotor3), 'POLAND')
((1, 1, 1), ('EGZWVONAHDCLFQMSIPJBYUKXTR', 'FOBHMDKEXQNRAULPGSJVTYICZW', \
'ZJXESIUQLHAVRMDOYGTNFWPBKC'), \
{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'})
:param rotpos: rotor_positon
:param rotsel: rotor_selection
:param pb: plugb -> validated and transformed
:return: (`rotpos`, `rotsel`, `pb`)
"""
# Checks if there are 3 unique rotors
if (unique_rotsel := len(set(rotsel))) < 3:
msg = f"Please use 3 unique rotors (not {unique_rotsel})"
raise Exception(msg)
# Checks if rotor positions are valid
rotorpos1, rotorpos2, rotorpos3 = rotpos
if not 0 < rotorpos1 <= len(abc):
msg = f"First rotor position is not within range of 1..26 ({rotorpos1}"
raise ValueError(msg)
if not 0 < rotorpos2 <= len(abc):
msg = f"Second rotor position is not within range of 1..26 ({rotorpos2})"
raise ValueError(msg)
if not 0 < rotorpos3 <= len(abc):
msg = f"Third rotor position is not within range of 1..26 ({rotorpos3})"
raise ValueError(msg)
# Validates string and returns dict
pbdict = _plugboard(pb)
return rotpos, rotsel, pbdict
def _plugboard(pbstring: str) -> dict[str, str]:
"""
https://en.wikipedia.org/wiki/Enigma_machine#Plugboard
>>> _plugboard('PICTURES')
{'P': 'I', 'I': 'P', 'C': 'T', 'T': 'C', 'U': 'R', 'R': 'U', 'E': 'S', 'S': 'E'}
>>> _plugboard('POLAND')
{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'}
In the code, ``pb`` stands for ``plugboard``
Pairs can be separated by spaces
:param pbstring: string containing plugboard setting for the Enigma machine
:return: dictionary containing converted pairs
"""
# tests the input string if it
# a) is type string
# b) has even length (so pairs can be made)
if not isinstance(pbstring, str):
msg = f"Plugboard setting isn't type string ({type(pbstring)})"
raise TypeError(msg)
elif len(pbstring) % 2 != 0:
msg = f"Odd number of symbols ({len(pbstring)})"
raise Exception(msg)
elif pbstring == "":
return {}
pbstring.replace(" ", "")
# Checks if all characters are unique
tmppbl = set()
for i in pbstring:
if i not in abc:
msg = f"'{i}' not in list of symbols"
raise Exception(msg)
elif i in tmppbl:
msg = f"Duplicate symbol ({i})"
raise Exception(msg)
else:
tmppbl.add(i)
del tmppbl
# Created the dictionary
pb = {}
for j in range(0, len(pbstring) - 1, 2):
pb[pbstring[j]] = pbstring[j + 1]
pb[pbstring[j + 1]] = pbstring[j]
return pb
def enigma(
text: str,
rotor_position: RotorPositionT,
rotor_selection: RotorSelectionT = (rotor1, rotor2, rotor3),
plugb: str = "",
) -> str:
"""
The only difference with real-world enigma is that ``I`` allowed string input.
All characters are converted to uppercase. (non-letter symbol are ignored)
| How it works:
| (for every letter in the message)
- Input letter goes into the plugboard.
If it is connected to another one, switch it.
- Letter goes through ``3`` rotors.
Each rotor can be represented as ``2`` sets of symbol, where one is shuffled.
Each symbol from the first set has corresponding symbol in
the second set and vice versa.
example::
| ABCDEFGHIJKLMNOPQRSTUVWXYZ | e.g. F=D and D=F
| VKLEPDBGRNWTFCJOHQAMUZYIXS |
- Symbol then goes through reflector (static rotor).
There it is switched with paired symbol.
The reflector can be represented as ``2`` sets, each with half of the alphanet.
There are usually ``10`` pairs of letters.
Example::
| ABCDEFGHIJKLM | e.g. E is paired to X
| ZYXWVUTSRQPON | so when E goes in X goes out and vice versa
- Letter then goes through the rotors again
- If the letter is connected to plugboard, it is switched.
- Return the letter
>>> enigma('Hello World!', (1, 2, 1), plugb='pictures')
'KORYH JUHHI!'
>>> enigma('KORYH, juhhi!', (1, 2, 1), plugb='pictures')
'HELLO, WORLD!'
>>> enigma('hello world!', (1, 1, 1), plugb='pictures')
'FPNCZ QWOBU!'
>>> enigma('FPNCZ QWOBU', (1, 1, 1), plugb='pictures')
'HELLO WORLD'
:param text: input message
:param rotor_position: tuple with ``3`` values in range ``1``.. ``26``
:param rotor_selection: tuple with ``3`` rotors
:param plugb: string containing plugboard configuration (default ``''``)
:return: en/decrypted string
"""
text = text.upper()
rotor_position, rotor_selection, plugboard = _validator(
rotor_position, rotor_selection, plugb.upper()
)
rotorpos1, rotorpos2, rotorpos3 = rotor_position
rotor1, rotor2, rotor3 = rotor_selection
rotorpos1 -= 1
rotorpos2 -= 1
rotorpos3 -= 1
result = []
# encryption/decryption process --------------------------
for symbol in text:
if symbol in abc:
# 1st plugboard --------------------------
if symbol in plugboard:
symbol = plugboard[symbol]
# rotor ra --------------------------
index = abc.index(symbol) + rotorpos1
symbol = rotor1[index % len(abc)]
# rotor rb --------------------------
index = abc.index(symbol) + rotorpos2
symbol = rotor2[index % len(abc)]
# rotor rc --------------------------
index = abc.index(symbol) + rotorpos3
symbol = rotor3[index % len(abc)]
# reflector --------------------------
# this is the reason you don't need another machine to decipher
symbol = reflector[symbol]
# 2nd rotors
symbol = abc[rotor3.index(symbol) - rotorpos3]
symbol = abc[rotor2.index(symbol) - rotorpos2]
symbol = abc[rotor1.index(symbol) - rotorpos1]
# 2nd plugboard
if symbol in plugboard:
symbol = plugboard[symbol]
# moves/resets rotor positions
rotorpos1 += 1
if rotorpos1 >= len(abc):
rotorpos1 = 0
rotorpos2 += 1
if rotorpos2 >= len(abc):
rotorpos2 = 0
rotorpos3 += 1
if rotorpos3 >= len(abc):
rotorpos3 = 0
# else:
# pass
# Error could be also raised
# raise ValueError(
# 'Invalid symbol('+repr(symbol)+')')
result.append(symbol)
return "".join(result)
if __name__ == "__main__":
message = "This is my Python script that emulates the Enigma machine from WWII."
rotor_pos = (1, 1, 1)
pb = "pictures"
rotor_sel = (rotor2, rotor4, rotor8)
en = enigma(message, rotor_pos, rotor_sel, pb)
print("Encrypted message:", en)
print("Decrypted message:", enigma(en, rotor_pos, rotor_sel, pb))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/rot13.py | ciphers/rot13.py | def dencrypt(s: str, n: int = 13) -> str:
"""
https://en.wikipedia.org/wiki/ROT13
>>> msg = "My secret bank account number is 173-52946 so don't tell anyone!!"
>>> s = dencrypt(msg)
>>> s
"Zl frperg onax nppbhag ahzore vf 173-52946 fb qba'g gryy nalbar!!"
>>> dencrypt(s) == msg
True
"""
out = ""
for c in s:
if "A" <= c <= "Z":
out += chr(ord("A") + (ord(c) - ord("A") + n) % 26)
elif "a" <= c <= "z":
out += chr(ord("a") + (ord(c) - ord("a") + n) % 26)
else:
out += c
return out
def main() -> None:
s0 = input("Enter message: ")
s1 = dencrypt(s0, 13)
print("Encryption:", s1)
s2 = dencrypt(s1, 13)
print("Decryption: ", s2)
if __name__ == "__main__":
import doctest
doctest.testmod()
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/brute_force_caesar_cipher.py | ciphers/brute_force_caesar_cipher.py | import string
def decrypt(message: str) -> None:
"""
>>> decrypt('TMDETUX PMDVU')
Decryption using Key #0: TMDETUX PMDVU
Decryption using Key #1: SLCDSTW OLCUT
Decryption using Key #2: RKBCRSV NKBTS
Decryption using Key #3: QJABQRU MJASR
Decryption using Key #4: PIZAPQT LIZRQ
Decryption using Key #5: OHYZOPS KHYQP
Decryption using Key #6: NGXYNOR JGXPO
Decryption using Key #7: MFWXMNQ IFWON
Decryption using Key #8: LEVWLMP HEVNM
Decryption using Key #9: KDUVKLO GDUML
Decryption using Key #10: JCTUJKN FCTLK
Decryption using Key #11: IBSTIJM EBSKJ
Decryption using Key #12: HARSHIL DARJI
Decryption using Key #13: GZQRGHK CZQIH
Decryption using Key #14: FYPQFGJ BYPHG
Decryption using Key #15: EXOPEFI AXOGF
Decryption using Key #16: DWNODEH ZWNFE
Decryption using Key #17: CVMNCDG YVMED
Decryption using Key #18: BULMBCF XULDC
Decryption using Key #19: ATKLABE WTKCB
Decryption using Key #20: ZSJKZAD VSJBA
Decryption using Key #21: YRIJYZC URIAZ
Decryption using Key #22: XQHIXYB TQHZY
Decryption using Key #23: WPGHWXA SPGYX
Decryption using Key #24: VOFGVWZ ROFXW
Decryption using Key #25: UNEFUVY QNEWV
"""
for key in range(len(string.ascii_uppercase)):
translated = ""
for symbol in message:
if symbol in string.ascii_uppercase:
num = string.ascii_uppercase.find(symbol)
num = num - key
if num < 0:
num = num + len(string.ascii_uppercase)
translated = translated + string.ascii_uppercase[num]
else:
translated = translated + symbol
print(f"Decryption using Key #{key}: {translated}")
def main() -> None:
message = input("Encrypted message: ")
message = message.upper()
decrypt(message)
if __name__ == "__main__":
import doctest
doctest.testmod()
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/decrypt_caesar_with_chi_squared.py | ciphers/decrypt_caesar_with_chi_squared.py | #!/usr/bin/env python3
from __future__ import annotations
def decrypt_caesar_with_chi_squared(
ciphertext: str,
cipher_alphabet: list[str] | None = None,
frequencies_dict: dict[str, float] | None = None,
case_sensitive: bool = False,
) -> tuple[int, float, str]:
"""
Basic Usage
===========
Arguments:
* `ciphertext` (str): the text to decode (encoded with the caesar cipher)
Optional Arguments:
* `cipher_alphabet` (list): the alphabet used for the cipher (each letter is
a string separated by commas)
* `frequencies_dict` (dict): a dictionary of word frequencies where keys are
the letters and values are a percentage representation of the frequency as
a decimal/float
* `case_sensitive` (bool): a boolean value: ``True`` if the case matters during
decryption, ``False`` if it doesn't
Returns:
* A tuple in the form of:
(`most_likely_cipher`, `most_likely_cipher_chi_squared_value`,
`decoded_most_likely_cipher`)
where...
- `most_likely_cipher` is an integer representing the shift of the smallest
chi-squared statistic (most likely key)
- `most_likely_cipher_chi_squared_value` is a float representing the
chi-squared statistic of the most likely shift
- `decoded_most_likely_cipher` is a string with the decoded cipher
(decoded by the most_likely_cipher key)
The Chi-squared test
====================
The caesar cipher
-----------------
The caesar cipher is a very insecure encryption algorithm, however it has
been used since Julius Caesar. The cipher is a simple substitution cipher
where each character in the plain text is replaced by a character in the
alphabet a certain number of characters after the original character. The
number of characters away is called the shift or key. For example:
| Plain text: ``hello``
| Key: ``1``
| Cipher text: ``ifmmp``
| (each letter in ``hello`` has been shifted one to the right in the eng. alphabet)
As you can imagine, this doesn't provide lots of security. In fact
decrypting ciphertext by brute-force is extremely easy even by hand. However
one way to do that is the chi-squared test.
The chi-squared test
--------------------
Each letter in the english alphabet has a frequency, or the amount of times
it shows up compared to other letters (usually expressed as a decimal
representing the percentage likelihood). The most common letter in the
english language is ``e`` with a frequency of ``0.11162`` or ``11.162%``.
The test is completed in the following fashion.
1. The ciphertext is decoded in a brute force way (every combination of the
``26`` possible combinations)
2. For every combination, for each letter in the combination, the average
amount of times the letter should appear the message is calculated by
multiplying the total number of characters by the frequency of the letter.
| For example:
| In a message of ``100`` characters, ``e`` should appear around ``11.162``
times.
3. Then, to calculate the margin of error (the amount of times the letter
SHOULD appear with the amount of times the letter DOES appear), we use
the chi-squared test. The following formula is used:
Let:
- n be the number of times the letter actually appears
- p be the predicted value of the number of times the letter should
appear (see item ``2``)
- let v be the chi-squared test result (referred to here as chi-squared
value/statistic)
::
(n - p)^2
--------- = v
p
4. Each chi squared value for each letter is then added up to the total.
The total is the chi-squared statistic for that encryption key.
5. The encryption key with the lowest chi-squared value is the most likely
to be the decoded answer.
Further Reading
===============
* http://practicalcryptography.com/cryptanalysis/text-characterisation/chi-squared-statistic/
* https://en.wikipedia.org/wiki/Letter_frequency
* https://en.wikipedia.org/wiki/Chi-squared_test
* https://en.m.wikipedia.org/wiki/Caesar_cipher
Doctests
========
>>> decrypt_caesar_with_chi_squared(
... 'dof pz aol jhlzhy jpwoly zv wvwbshy? pa pz avv lhzf av jyhjr!'
... ) # doctest: +NORMALIZE_WHITESPACE
(7, 3129.228005747531,
'why is the caesar cipher so popular? it is too easy to crack!')
>>> decrypt_caesar_with_chi_squared('crybd cdbsxq')
(10, 233.35343938980898, 'short string')
>>> decrypt_caesar_with_chi_squared('Crybd Cdbsxq', case_sensitive=True)
(10, 233.35343938980898, 'Short String')
>>> decrypt_caesar_with_chi_squared(12)
Traceback (most recent call last):
AttributeError: 'int' object has no attribute 'lower'
"""
alphabet_letters = cipher_alphabet or [chr(i) for i in range(97, 123)]
# If the argument is None or the user provided an empty dictionary
if not frequencies_dict:
# Frequencies of letters in the english language (how much they show up)
frequencies = {
"a": 0.08497,
"b": 0.01492,
"c": 0.02202,
"d": 0.04253,
"e": 0.11162,
"f": 0.02228,
"g": 0.02015,
"h": 0.06094,
"i": 0.07546,
"j": 0.00153,
"k": 0.01292,
"l": 0.04025,
"m": 0.02406,
"n": 0.06749,
"o": 0.07507,
"p": 0.01929,
"q": 0.00095,
"r": 0.07587,
"s": 0.06327,
"t": 0.09356,
"u": 0.02758,
"v": 0.00978,
"w": 0.02560,
"x": 0.00150,
"y": 0.01994,
"z": 0.00077,
}
else:
# Custom frequencies dictionary
frequencies = frequencies_dict
if not case_sensitive:
ciphertext = ciphertext.lower()
# Chi squared statistic values
chi_squared_statistic_values: dict[int, tuple[float, str]] = {}
# cycle through all of the shifts
for shift in range(len(alphabet_letters)):
decrypted_with_shift = ""
# decrypt the message with the shift
for letter in ciphertext:
try:
# Try to index the letter in the alphabet
new_key = (alphabet_letters.index(letter.lower()) - shift) % len(
alphabet_letters
)
decrypted_with_shift += (
alphabet_letters[new_key].upper()
if case_sensitive and letter.isupper()
else alphabet_letters[new_key]
)
except ValueError:
# Append the character if it isn't in the alphabet
decrypted_with_shift += letter
chi_squared_statistic = 0.0
# Loop through each letter in the decoded message with the shift
for letter in decrypted_with_shift:
if case_sensitive:
letter = letter.lower()
if letter in frequencies:
# Get the amount of times the letter occurs in the message
occurrences = decrypted_with_shift.lower().count(letter)
# Get the excepcted amount of times the letter should appear based
# on letter frequencies
expected = frequencies[letter] * occurrences
# Complete the chi squared statistic formula
chi_letter_value = ((occurrences - expected) ** 2) / expected
# Add the margin of error to the total chi squared statistic
chi_squared_statistic += chi_letter_value
elif letter.lower() in frequencies:
# Get the amount of times the letter occurs in the message
occurrences = decrypted_with_shift.count(letter)
# Get the excepcted amount of times the letter should appear based
# on letter frequencies
expected = frequencies[letter] * occurrences
# Complete the chi squared statistic formula
chi_letter_value = ((occurrences - expected) ** 2) / expected
# Add the margin of error to the total chi squared statistic
chi_squared_statistic += chi_letter_value
# Add the data to the chi_squared_statistic_values dictionary
chi_squared_statistic_values[shift] = (
chi_squared_statistic,
decrypted_with_shift,
)
# Get the most likely cipher by finding the cipher with the smallest chi squared
# statistic
def chi_squared_statistic_values_sorting_key(key: int) -> tuple[float, str]:
return chi_squared_statistic_values[key]
most_likely_cipher: int = min(
chi_squared_statistic_values,
key=chi_squared_statistic_values_sorting_key,
)
# Get all the data from the most likely cipher (key, decoded message)
(
most_likely_cipher_chi_squared_value,
decoded_most_likely_cipher,
) = chi_squared_statistic_values[most_likely_cipher]
# Return the data on the most likely shift
return (
most_likely_cipher,
most_likely_cipher_chi_squared_value,
decoded_most_likely_cipher,
)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/playfair_cipher.py | ciphers/playfair_cipher.py | """
https://en.wikipedia.org/wiki/Playfair_cipher#Description
The Playfair cipher was developed by Charles Wheatstone in 1854
It's use was heavily promotedby Lord Playfair, hence its name
Some features of the Playfair cipher are:
1) It was the first literal diagram substitution cipher
2) It is a manual symmetric encryption technique
3) It is a multiple letter encryption cipher
The implementation in the code below encodes alphabets only.
It removes spaces, special characters and numbers from the
code.
Playfair is no longer used by military forces because of known
insecurities and of the advent of automated encryption devices.
This cipher is regarded as insecure since before World War I.
"""
import itertools
import string
from collections.abc import Generator, Iterable
def chunker(seq: Iterable[str], size: int) -> Generator[tuple[str, ...]]:
it = iter(seq)
while True:
chunk = tuple(itertools.islice(it, size))
if not chunk:
return
yield chunk
def prepare_input(dirty: str) -> str:
"""
Prepare the plaintext by up-casing it
and separating repeated letters with X's
"""
dirty = "".join([c.upper() for c in dirty if c in string.ascii_letters])
clean = ""
if len(dirty) < 2:
return dirty
for i in range(len(dirty) - 1):
clean += dirty[i]
if dirty[i] == dirty[i + 1]:
clean += "X"
clean += dirty[-1]
if len(clean) & 1:
clean += "X"
return clean
def generate_table(key: str) -> list[str]:
# I and J are used interchangeably to allow
# us to use a 5x5 table (25 letters)
alphabet = "ABCDEFGHIKLMNOPQRSTUVWXYZ"
# we're using a list instead of a '2d' array because it makes the math
# for setting up the table and doing the actual encoding/decoding simpler
table = []
# copy key chars into the table if they are in `alphabet` ignoring duplicates
for char in key.upper():
if char not in table and char in alphabet:
table.append(char)
# fill the rest of the table in with the remaining alphabet chars
for char in alphabet:
if char not in table:
table.append(char)
return table
def encode(plaintext: str, key: str) -> str:
"""
Encode the given plaintext using the Playfair cipher.
Takes the plaintext and the key as input and returns the encoded string.
>>> encode("Hello", "MONARCHY")
'CFSUPM'
>>> encode("attack on the left flank", "EMERGENCY")
'DQZSBYFSDZFMFNLOHFDRSG'
>>> encode("Sorry!", "SPECIAL")
'AVXETX'
>>> encode("Number 1", "NUMBER")
'UMBENF'
>>> encode("Photosynthesis!", "THE SUN")
'OEMHQHVCHESUKE'
"""
table = generate_table(key)
plaintext = prepare_input(plaintext)
ciphertext = ""
for char1, char2 in chunker(plaintext, 2):
row1, col1 = divmod(table.index(char1), 5)
row2, col2 = divmod(table.index(char2), 5)
if row1 == row2:
ciphertext += table[row1 * 5 + (col1 + 1) % 5]
ciphertext += table[row2 * 5 + (col2 + 1) % 5]
elif col1 == col2:
ciphertext += table[((row1 + 1) % 5) * 5 + col1]
ciphertext += table[((row2 + 1) % 5) * 5 + col2]
else: # rectangle
ciphertext += table[row1 * 5 + col2]
ciphertext += table[row2 * 5 + col1]
return ciphertext
def decode(ciphertext: str, key: str) -> str:
"""
Decode the input string using the provided key.
>>> decode("BMZFAZRZDH", "HAZARD")
'FIREHAZARD'
>>> decode("HNBWBPQT", "AUTOMOBILE")
'DRIVINGX'
>>> decode("SLYSSAQS", "CASTLE")
'ATXTACKX'
"""
table = generate_table(key)
plaintext = ""
for char1, char2 in chunker(ciphertext, 2):
row1, col1 = divmod(table.index(char1), 5)
row2, col2 = divmod(table.index(char2), 5)
if row1 == row2:
plaintext += table[row1 * 5 + (col1 - 1) % 5]
plaintext += table[row2 * 5 + (col2 - 1) % 5]
elif col1 == col2:
plaintext += table[((row1 - 1) % 5) * 5 + col1]
plaintext += table[((row2 - 1) % 5) * 5 + col2]
else: # rectangle
plaintext += table[row1 * 5 + col2]
plaintext += table[row2 * 5 + col1]
return plaintext
if __name__ == "__main__":
import doctest
doctest.testmod()
print("Encoded:", encode("BYE AND THANKS", "GREETING"))
print("Decoded:", decode("CXRBANRLBALQ", "GREETING"))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/onepad_cipher.py | ciphers/onepad_cipher.py | import random
class Onepad:
@staticmethod
def encrypt(text: str) -> tuple[list[int], list[int]]:
"""
Function to encrypt text using pseudo-random numbers
>>> Onepad().encrypt("")
([], [])
>>> Onepad().encrypt([])
([], [])
>>> random.seed(1)
>>> Onepad().encrypt(" ")
([6969], [69])
>>> random.seed(1)
>>> Onepad().encrypt("Hello")
([9729, 114756, 4653, 31309, 10492], [69, 292, 33, 131, 61])
>>> Onepad().encrypt(1)
Traceback (most recent call last):
...
TypeError: 'int' object is not iterable
>>> Onepad().encrypt(1.1)
Traceback (most recent call last):
...
TypeError: 'float' object is not iterable
"""
plain = [ord(i) for i in text]
key = []
cipher = []
for i in plain:
k = random.randint(1, 300)
c = (i + k) * k
cipher.append(c)
key.append(k)
return cipher, key
@staticmethod
def decrypt(cipher: list[int], key: list[int]) -> str:
"""
Function to decrypt text using pseudo-random numbers.
>>> Onepad().decrypt([], [])
''
>>> Onepad().decrypt([35], [])
''
>>> Onepad().decrypt([], [35])
Traceback (most recent call last):
...
IndexError: list index out of range
>>> random.seed(1)
>>> Onepad().decrypt([9729, 114756, 4653, 31309, 10492], [69, 292, 33, 131, 61])
'Hello'
"""
plain = []
for i in range(len(key)):
p = int((cipher[i] - (key[i]) ** 2) / key[i])
plain.append(chr(p))
return "".join(plain)
if __name__ == "__main__":
c, k = Onepad().encrypt("Hello")
print(c, k)
print(Onepad().decrypt(c, k))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/base16.py | ciphers/base16.py | def base16_encode(data: bytes) -> str:
"""
Encodes the given bytes into base16.
>>> base16_encode(b'Hello World!')
'48656C6C6F20576F726C6421'
>>> base16_encode(b'HELLO WORLD!')
'48454C4C4F20574F524C4421'
>>> base16_encode(b'')
''
"""
# Turn the data into a list of integers (where each integer is a byte),
# Then turn each byte into its hexadecimal representation, make sure
# it is uppercase, and then join everything together and return it.
return "".join([hex(byte)[2:].zfill(2).upper() for byte in list(data)])
def base16_decode(data: str) -> bytes:
"""
Decodes the given base16 encoded data into bytes.
>>> base16_decode('48656C6C6F20576F726C6421')
b'Hello World!'
>>> base16_decode('48454C4C4F20574F524C4421')
b'HELLO WORLD!'
>>> base16_decode('')
b''
>>> base16_decode('486')
Traceback (most recent call last):
...
ValueError: Base16 encoded data is invalid:
Data does not have an even number of hex digits.
>>> base16_decode('48656c6c6f20576f726c6421')
Traceback (most recent call last):
...
ValueError: Base16 encoded data is invalid:
Data is not uppercase hex or it contains invalid characters.
>>> base16_decode('This is not base64 encoded data.')
Traceback (most recent call last):
...
ValueError: Base16 encoded data is invalid:
Data is not uppercase hex or it contains invalid characters.
"""
# Check data validity, following RFC3548
# https://www.ietf.org/rfc/rfc3548.txt
if (len(data) % 2) != 0:
raise ValueError(
"""Base16 encoded data is invalid:
Data does not have an even number of hex digits."""
)
# Check the character set - the standard base16 alphabet
# is uppercase according to RFC3548 section 6
if not set(data) <= set("0123456789ABCDEF"):
raise ValueError(
"""Base16 encoded data is invalid:
Data is not uppercase hex or it contains invalid characters."""
)
# For every two hexadecimal digits (= a byte), turn it into an integer.
# Then, string the result together into bytes, and return it.
return bytes(int(data[i] + data[i + 1], 16) for i in range(0, len(data), 2))
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/morse_code.py | ciphers/morse_code.py | #!/usr/bin/env python3
"""
Python program to translate to and from Morse code.
https://en.wikipedia.org/wiki/Morse_code
"""
# fmt: off
MORSE_CODE_DICT = {
"A": ".-", "B": "-...", "C": "-.-.", "D": "-..", "E": ".", "F": "..-.", "G": "--.",
"H": "....", "I": "..", "J": ".---", "K": "-.-", "L": ".-..", "M": "--", "N": "-.",
"O": "---", "P": ".--.", "Q": "--.-", "R": ".-.", "S": "...", "T": "-", "U": "..-",
"V": "...-", "W": ".--", "X": "-..-", "Y": "-.--", "Z": "--..", "1": ".----",
"2": "..---", "3": "...--", "4": "....-", "5": ".....", "6": "-....", "7": "--...",
"8": "---..", "9": "----.", "0": "-----", "&": ".-...", "@": ".--.-.",
":": "---...", ",": "--..--", ".": ".-.-.-", "'": ".----.", '"': ".-..-.",
"?": "..--..", "/": "-..-.", "=": "-...-", "+": ".-.-.", "-": "-....-",
"(": "-.--.", ")": "-.--.-", "!": "-.-.--", " ": "/"
} # Exclamation mark is not in ITU-R recommendation
# fmt: on
REVERSE_DICT = {value: key for key, value in MORSE_CODE_DICT.items()}
def encrypt(message: str) -> str:
"""
>>> encrypt("Sos!")
'... --- ... -.-.--'
>>> encrypt("SOS!") == encrypt("sos!")
True
"""
return " ".join(MORSE_CODE_DICT[char] for char in message.upper())
def decrypt(message: str) -> str:
"""
>>> decrypt('... --- ... -.-.--')
'SOS!'
"""
return "".join(REVERSE_DICT[char] for char in message.split())
def main() -> None:
"""
>>> s = "".join(MORSE_CODE_DICT)
>>> decrypt(encrypt(s)) == s
True
"""
message = "Morse code here!"
print(message)
message = encrypt(message)
print(message)
message = decrypt(message)
print(message)
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/bifid.py | ciphers/bifid.py | #!/usr/bin/env python3
"""
The Bifid Cipher uses a Polybius Square to encipher a message in a way that
makes it fairly difficult to decipher without knowing the secret.
https://www.braingle.com/brainteasers/codes/bifid.php
"""
import numpy as np
SQUARE = [
["a", "b", "c", "d", "e"],
["f", "g", "h", "i", "k"],
["l", "m", "n", "o", "p"],
["q", "r", "s", "t", "u"],
["v", "w", "x", "y", "z"],
]
class BifidCipher:
def __init__(self) -> None:
self.SQUARE = np.array(SQUARE)
def letter_to_numbers(self, letter: str) -> np.ndarray:
"""
Return the pair of numbers that represents the given letter in the
polybius square
>>> np.array_equal(BifidCipher().letter_to_numbers('a'), [1,1])
True
>>> np.array_equal(BifidCipher().letter_to_numbers('u'), [4,5])
True
"""
index1, index2 = np.where(letter == self.SQUARE)
indexes = np.concatenate([index1 + 1, index2 + 1])
return indexes
def numbers_to_letter(self, index1: int, index2: int) -> str:
"""
Return the letter corresponding to the position [index1, index2] in
the polybius square
>>> BifidCipher().numbers_to_letter(4, 5) == "u"
True
>>> BifidCipher().numbers_to_letter(1, 1) == "a"
True
"""
letter = self.SQUARE[index1 - 1, index2 - 1]
return letter
def encode(self, message: str) -> str:
"""
Return the encoded version of message according to the polybius cipher
>>> BifidCipher().encode('testmessage') == 'qtltbdxrxlk'
True
>>> BifidCipher().encode('Test Message') == 'qtltbdxrxlk'
True
>>> BifidCipher().encode('test j') == BifidCipher().encode('test i')
True
"""
message = message.lower()
message = message.replace(" ", "")
message = message.replace("j", "i")
first_step = np.empty((2, len(message)))
for letter_index in range(len(message)):
numbers = self.letter_to_numbers(message[letter_index])
first_step[0, letter_index] = numbers[0]
first_step[1, letter_index] = numbers[1]
second_step = first_step.reshape(2 * len(message))
encoded_message = ""
for numbers_index in range(len(message)):
index1 = int(second_step[numbers_index * 2])
index2 = int(second_step[(numbers_index * 2) + 1])
letter = self.numbers_to_letter(index1, index2)
encoded_message = encoded_message + letter
return encoded_message
def decode(self, message: str) -> str:
"""
Return the decoded version of message according to the polybius cipher
>>> BifidCipher().decode('qtltbdxrxlk') == 'testmessage'
True
"""
message = message.lower()
message.replace(" ", "")
first_step = np.empty(2 * len(message))
for letter_index in range(len(message)):
numbers = self.letter_to_numbers(message[letter_index])
first_step[letter_index * 2] = numbers[0]
first_step[letter_index * 2 + 1] = numbers[1]
second_step = first_step.reshape((2, len(message)))
decoded_message = ""
for numbers_index in range(len(message)):
index1 = int(second_step[0, numbers_index])
index2 = int(second_step[1, numbers_index])
letter = self.numbers_to_letter(index1, index2)
decoded_message = decoded_message + letter
return decoded_message
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/shuffled_shift_cipher.py | ciphers/shuffled_shift_cipher.py | from __future__ import annotations
import random
import string
class ShuffledShiftCipher:
"""
This algorithm uses the Caesar Cipher algorithm but removes the option to
use brute force to decrypt the message.
The passcode is a random password from the selection buffer of
1. uppercase letters of the English alphabet
2. lowercase letters of the English alphabet
3. digits from 0 to 9
Using unique characters from the passcode, the normal list of characters,
that can be allowed in the plaintext, is pivoted and shuffled. Refer to docstring
of __make_key_list() to learn more about the shuffling.
Then, using the passcode, a number is calculated which is used to encrypt the
plaintext message with the normal shift cipher method, only in this case, the
reference, to look back at while decrypting, is shuffled.
Each cipher object can possess an optional argument as passcode, without which a
new passcode is generated for that object automatically.
cip1 = ShuffledShiftCipher('d4usr9TWxw9wMD')
cip2 = ShuffledShiftCipher()
"""
def __init__(self, passcode: str | None = None) -> None:
"""
Initializes a cipher object with a passcode as it's entity
Note: No new passcode is generated if user provides a passcode
while creating the object
"""
self.__passcode = passcode or self.__passcode_creator()
self.__key_list = self.__make_key_list()
self.__shift_key = self.__make_shift_key()
def __str__(self) -> str:
"""
:return: passcode of the cipher object
"""
return "".join(self.__passcode)
def __neg_pos(self, iterlist: list[int]) -> list[int]:
"""
Mutates the list by changing the sign of each alternate element
:param iterlist: takes a list iterable
:return: the mutated list
"""
for i in range(1, len(iterlist), 2):
iterlist[i] *= -1
return iterlist
def __passcode_creator(self) -> list[str]:
"""
Creates a random password from the selection buffer of
1. uppercase letters of the English alphabet
2. lowercase letters of the English alphabet
3. digits from 0 to 9
:rtype: list
:return: a password of a random length between 10 to 20
"""
choices = string.ascii_letters + string.digits
password = [random.choice(choices) for _ in range(random.randint(10, 20))]
return password
def __make_key_list(self) -> list[str]:
"""
Shuffles the ordered character choices by pivoting at breakpoints
Breakpoints are the set of characters in the passcode
eg:
if, ABCDEFGHIJKLMNOPQRSTUVWXYZ are the possible characters
and CAMERA is the passcode
then, breakpoints = [A,C,E,M,R] # sorted set of characters from passcode
shuffled parts: [A,CB,ED,MLKJIHGF,RQPON,ZYXWVUTS]
shuffled __key_list : ACBEDMLKJIHGFRQPONZYXWVUTS
Shuffling only 26 letters of the english alphabet can generate 26!
combinations for the shuffled list. In the program we consider, a set of
97 characters (including letters, digits, punctuation and whitespaces),
thereby creating a possibility of 97! combinations (which is a 152 digit number
in itself), thus diminishing the possibility of a brute force approach.
Moreover, shift keys even introduce a multiple of 26 for a brute force approach
for each of the already 97! combinations.
"""
# key_list_options contain nearly all printable except few elements from
# string.whitespace
key_list_options = (
string.ascii_letters + string.digits + string.punctuation + " \t\n"
)
keys_l = []
# creates points known as breakpoints to break the key_list_options at those
# points and pivot each substring
breakpoints = sorted(set(self.__passcode))
temp_list: list[str] = []
# algorithm for creating a new shuffled list, keys_l, out of key_list_options
for i in key_list_options:
temp_list.extend(i)
# checking breakpoints at which to pivot temporary sublist and add it into
# keys_l
if i in breakpoints or i == key_list_options[-1]:
keys_l.extend(temp_list[::-1])
temp_list.clear()
# returning a shuffled keys_l to prevent brute force guessing of shift key
return keys_l
def __make_shift_key(self) -> int:
"""
sum() of the mutated list of ascii values of all characters where the
mutated list is the one returned by __neg_pos()
"""
num = sum(self.__neg_pos([ord(x) for x in self.__passcode]))
return num if num > 0 else len(self.__passcode)
def decrypt(self, encoded_message: str) -> str:
"""
Performs shifting of the encoded_message w.r.t. the shuffled __key_list
to create the decoded_message
>>> ssc = ShuffledShiftCipher('4PYIXyqeQZr44')
>>> ssc.decrypt("d>**-1z6&'5z'5z:z+-='$'>=zp:>5:#z<'.&>#")
'Hello, this is a modified Caesar cipher'
"""
decoded_message = ""
# decoding shift like Caesar cipher algorithm implementing negative shift or
# reverse shift or left shift
for i in encoded_message:
position = self.__key_list.index(i)
decoded_message += self.__key_list[
(position - self.__shift_key) % -len(self.__key_list)
]
return decoded_message
def encrypt(self, plaintext: str) -> str:
"""
Performs shifting of the plaintext w.r.t. the shuffled __key_list
to create the encoded_message
>>> ssc = ShuffledShiftCipher('4PYIXyqeQZr44')
>>> ssc.encrypt('Hello, this is a modified Caesar cipher')
"d>**-1z6&'5z'5z:z+-='$'>=zp:>5:#z<'.&>#"
"""
encoded_message = ""
# encoding shift like Caesar cipher algorithm implementing positive shift or
# forward shift or right shift
for i in plaintext:
position = self.__key_list.index(i)
encoded_message += self.__key_list[
(position + self.__shift_key) % len(self.__key_list)
]
return encoded_message
def test_end_to_end(msg: str = "Hello, this is a modified Caesar cipher") -> str:
"""
>>> test_end_to_end()
'Hello, this is a modified Caesar cipher'
"""
cip1 = ShuffledShiftCipher()
return cip1.decrypt(cip1.encrypt(msg))
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/mixed_keyword_cypher.py | ciphers/mixed_keyword_cypher.py | from string import ascii_uppercase
def mixed_keyword(
keyword: str, plaintext: str, verbose: bool = False, alphabet: str = ascii_uppercase
) -> str:
"""
For keyword: hello
H E L O
A B C D
F G I J
K M N P
Q R S T
U V W X
Y Z
and map vertically
>>> mixed_keyword("college", "UNIVERSITY", True) # doctest: +NORMALIZE_WHITESPACE
{'A': 'C', 'B': 'A', 'C': 'I', 'D': 'P', 'E': 'U', 'F': 'Z', 'G': 'O', 'H': 'B',
'I': 'J', 'J': 'Q', 'K': 'V', 'L': 'L', 'M': 'D', 'N': 'K', 'O': 'R', 'P': 'W',
'Q': 'E', 'R': 'F', 'S': 'M', 'T': 'S', 'U': 'X', 'V': 'G', 'W': 'H', 'X': 'N',
'Y': 'T', 'Z': 'Y'}
'XKJGUFMJST'
>>> mixed_keyword("college", "UNIVERSITY", False) # doctest: +NORMALIZE_WHITESPACE
'XKJGUFMJST'
"""
keyword = keyword.upper()
plaintext = plaintext.upper()
alphabet_set = set(alphabet)
# create a list of unique characters in the keyword - their order matters
# it determines how we will map plaintext characters to the ciphertext
unique_chars = []
for char in keyword:
if char in alphabet_set and char not in unique_chars:
unique_chars.append(char)
# the number of those unique characters will determine the number of rows
num_unique_chars_in_keyword = len(unique_chars)
# create a shifted version of the alphabet
shifted_alphabet = unique_chars + [
char for char in alphabet if char not in unique_chars
]
# create a modified alphabet by splitting the shifted alphabet into rows
modified_alphabet = [
shifted_alphabet[k : k + num_unique_chars_in_keyword]
for k in range(0, 26, num_unique_chars_in_keyword)
]
# map the alphabet characters to the modified alphabet characters
# going 'vertically' through the modified alphabet - consider columns first
mapping = {}
letter_index = 0
for column in range(num_unique_chars_in_keyword):
for row in modified_alphabet:
# if current row (the last one) is too short, break out of loop
if len(row) <= column:
break
# map current letter to letter in modified alphabet
mapping[alphabet[letter_index]] = row[column]
letter_index += 1
if verbose:
print(mapping)
# create the encrypted text by mapping the plaintext to the modified alphabet
return "".join(mapping.get(char, char) for char in plaintext)
if __name__ == "__main__":
# example use
print(mixed_keyword("college", "UNIVERSITY"))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/transposition_cipher.py | ciphers/transposition_cipher.py | import math
"""
In cryptography, the TRANSPOSITION cipher is a method of encryption where the
positions of plaintext are shifted a certain number(determined by the key) that
follows a regular system that results in the permuted text, known as the encrypted
text. The type of transposition cipher demonstrated under is the ROUTE cipher.
"""
def main() -> None:
message = input("Enter message: ")
key = int(input(f"Enter key [2-{len(message) - 1}]: "))
mode = input("Encryption/Decryption [e/d]: ")
if mode.lower().startswith("e"):
text = encrypt_message(key, message)
elif mode.lower().startswith("d"):
text = decrypt_message(key, message)
# Append pipe symbol (vertical bar) to identify spaces at the end.
print(f"Output:\n{text + '|'}")
def encrypt_message(key: int, message: str) -> str:
"""
>>> encrypt_message(6, 'Harshil Darji')
'Hlia rDsahrij'
"""
cipher_text = [""] * key
for col in range(key):
pointer = col
while pointer < len(message):
cipher_text[col] += message[pointer]
pointer += key
return "".join(cipher_text)
def decrypt_message(key: int, message: str) -> str:
"""
>>> decrypt_message(6, 'Hlia rDsahrij')
'Harshil Darji'
"""
num_cols = math.ceil(len(message) / key)
num_rows = key
num_shaded_boxes = (num_cols * num_rows) - len(message)
plain_text = [""] * num_cols
col = 0
row = 0
for symbol in message:
plain_text[col] += symbol
col += 1
if (col == num_cols) or (
(col == num_cols - 1) and (row >= num_rows - num_shaded_boxes)
):
col = 0
row += 1
return "".join(plain_text)
if __name__ == "__main__":
import doctest
doctest.testmod()
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/rsa_cipher.py | ciphers/rsa_cipher.py | import os
import sys
from . import rsa_key_generator as rkg
DEFAULT_BLOCK_SIZE = 128
BYTE_SIZE = 256
def get_blocks_from_text(
message: str, block_size: int = DEFAULT_BLOCK_SIZE
) -> list[int]:
message_bytes = message.encode("ascii")
block_ints = []
for block_start in range(0, len(message_bytes), block_size):
block_int = 0
for i in range(block_start, min(block_start + block_size, len(message_bytes))):
block_int += message_bytes[i] * (BYTE_SIZE ** (i % block_size))
block_ints.append(block_int)
return block_ints
def get_text_from_blocks(
block_ints: list[int], message_length: int, block_size: int = DEFAULT_BLOCK_SIZE
) -> str:
message: list[str] = []
for block_int in block_ints:
block_message: list[str] = []
for i in range(block_size - 1, -1, -1):
if len(message) + i < message_length:
ascii_number = block_int // (BYTE_SIZE**i)
block_int = block_int % (BYTE_SIZE**i)
block_message.insert(0, chr(ascii_number))
message.extend(block_message)
return "".join(message)
def encrypt_message(
message: str, key: tuple[int, int], block_size: int = DEFAULT_BLOCK_SIZE
) -> list[int]:
encrypted_blocks = []
n, e = key
for block in get_blocks_from_text(message, block_size):
encrypted_blocks.append(pow(block, e, n))
return encrypted_blocks
def decrypt_message(
encrypted_blocks: list[int],
message_length: int,
key: tuple[int, int],
block_size: int = DEFAULT_BLOCK_SIZE,
) -> str:
decrypted_blocks = []
n, d = key
for block in encrypted_blocks:
decrypted_blocks.append(pow(block, d, n))
return get_text_from_blocks(decrypted_blocks, message_length, block_size)
def read_key_file(key_filename: str) -> tuple[int, int, int]:
with open(key_filename) as fo:
content = fo.read()
key_size, n, eor_d = content.split(",")
return (int(key_size), int(n), int(eor_d))
def encrypt_and_write_to_file(
message_filename: str,
key_filename: str,
message: str,
block_size: int = DEFAULT_BLOCK_SIZE,
) -> str:
key_size, n, e = read_key_file(key_filename)
if key_size < block_size * 8:
sys.exit(
f"ERROR: Block size is {block_size * 8} bits and key size is {key_size} "
"bits. The RSA cipher requires the block size to be equal to or greater "
"than the key size. Either decrease the block size or use different keys."
)
encrypted_blocks = [str(i) for i in encrypt_message(message, (n, e), block_size)]
encrypted_content = ",".join(encrypted_blocks)
encrypted_content = f"{len(message)}_{block_size}_{encrypted_content}"
with open(message_filename, "w") as fo:
fo.write(encrypted_content)
return encrypted_content
def read_from_file_and_decrypt(message_filename: str, key_filename: str) -> str:
key_size, n, d = read_key_file(key_filename)
with open(message_filename) as fo:
content = fo.read()
message_length_str, block_size_str, encrypted_message = content.split("_")
message_length = int(message_length_str)
block_size = int(block_size_str)
if key_size < block_size * 8:
sys.exit(
f"ERROR: Block size is {block_size * 8} bits and key size is {key_size} "
"bits. The RSA cipher requires the block size to be equal to or greater "
"than the key size. Were the correct key file and encrypted file specified?"
)
encrypted_blocks = []
for block in encrypted_message.split(","):
encrypted_blocks.append(int(block))
return decrypt_message(encrypted_blocks, message_length, (n, d), block_size)
def main() -> None:
filename = "encrypted_file.txt"
response = input(r"Encrypt\Decrypt [e\d]: ")
if response.lower().startswith("e"):
mode = "encrypt"
elif response.lower().startswith("d"):
mode = "decrypt"
if mode == "encrypt":
if not os.path.exists("rsa_pubkey.txt"):
rkg.make_key_files("rsa", 1024)
message = input("\nEnter message: ")
pubkey_filename = "rsa_pubkey.txt"
print(f"Encrypting and writing to {filename}...")
encrypted_text = encrypt_and_write_to_file(filename, pubkey_filename, message)
print("\nEncrypted text:")
print(encrypted_text)
elif mode == "decrypt":
privkey_filename = "rsa_privkey.txt"
print(f"Reading from {filename} and decrypting...")
decrypted_text = read_from_file_and_decrypt(filename, privkey_filename)
print("writing decryption to rsa_decryption.txt...")
with open("rsa_decryption.txt", "w") as dec:
dec.write(decrypted_text)
print("\nDecryption:")
print(decrypted_text)
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/gronsfeld_cipher.py | ciphers/gronsfeld_cipher.py | from string import ascii_uppercase
def gronsfeld(text: str, key: str) -> str:
"""
Encrypt plaintext with the Gronsfeld cipher
>>> gronsfeld('hello', '412')
'LFNPP'
>>> gronsfeld('hello', '123')
'IGOMQ'
>>> gronsfeld('', '123')
''
>>> gronsfeld('yes, ¥€$ - _!@#%?', '0')
'YES, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '01')
'YFS, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '012')
'YFU, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '')
Traceback (most recent call last):
...
ZeroDivisionError: division by zero
"""
ascii_len = len(ascii_uppercase)
key_len = len(key)
encrypted_text = ""
keys = [int(char) for char in key]
upper_case_text = text.upper()
for i, char in enumerate(upper_case_text):
if char in ascii_uppercase:
new_position = (ascii_uppercase.index(char) + keys[i % key_len]) % ascii_len
shifted_letter = ascii_uppercase[new_position]
encrypted_text += shifted_letter
else:
encrypted_text += char
return encrypted_text
if __name__ == "__main__":
from doctest import testmod
testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/ciphers/baconian_cipher.py | ciphers/baconian_cipher.py | """
Program to encode and decode Baconian or Bacon's Cipher
Wikipedia reference : https://en.wikipedia.org/wiki/Bacon%27s_cipher
"""
encode_dict = {
"a": "AAAAA",
"b": "AAAAB",
"c": "AAABA",
"d": "AAABB",
"e": "AABAA",
"f": "AABAB",
"g": "AABBA",
"h": "AABBB",
"i": "ABAAA",
"j": "BBBAA",
"k": "ABAAB",
"l": "ABABA",
"m": "ABABB",
"n": "ABBAA",
"o": "ABBAB",
"p": "ABBBA",
"q": "ABBBB",
"r": "BAAAA",
"s": "BAAAB",
"t": "BAABA",
"u": "BAABB",
"v": "BBBAB",
"w": "BABAA",
"x": "BABAB",
"y": "BABBA",
"z": "BABBB",
" ": " ",
}
decode_dict = {value: key for key, value in encode_dict.items()}
def encode(word: str) -> str:
"""
Encodes to Baconian cipher
>>> encode("hello")
'AABBBAABAAABABAABABAABBAB'
>>> encode("hello world")
'AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB'
>>> encode("hello world!")
Traceback (most recent call last):
...
Exception: encode() accepts only letters of the alphabet and spaces
"""
encoded = ""
for letter in word.lower():
if letter.isalpha() or letter == " ":
encoded += encode_dict[letter]
else:
raise Exception("encode() accepts only letters of the alphabet and spaces")
return encoded
def decode(coded: str) -> str:
"""
Decodes from Baconian cipher
>>> decode("AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB")
'hello world'
>>> decode("AABBBAABAAABABAABABAABBAB")
'hello'
>>> decode("AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB!")
Traceback (most recent call last):
...
Exception: decode() accepts only 'A', 'B' and spaces
"""
if set(coded) - {"A", "B", " "} != set():
raise Exception("decode() accepts only 'A', 'B' and spaces")
decoded = ""
for word in coded.split():
while len(word) != 0:
decoded += decode_dict[word[:5]]
word = word[5:]
decoded += " "
return decoded.strip()
if __name__ == "__main__":
from doctest import testmod
testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/audio_filters/show_response.py | audio_filters/show_response.py | from __future__ import annotations
from abc import abstractmethod
from math import pi
from typing import Protocol
import matplotlib.pyplot as plt
import numpy as np
class FilterType(Protocol):
@abstractmethod
def process(self, sample: float) -> float:
"""
Calculate y[n]
>>> issubclass(FilterType, Protocol)
True
"""
def get_bounds(
fft_results: np.ndarray, samplerate: int
) -> tuple[int | float, int | float]:
"""
Get bounds for printing fft results
>>> import numpy
>>> array = numpy.linspace(-20.0, 20.0, 1000)
>>> get_bounds(array, 1000)
(-20, 20)
"""
lowest = min([-20, np.min(fft_results[1 : samplerate // 2 - 1])])
highest = max([20, np.max(fft_results[1 : samplerate // 2 - 1])])
return lowest, highest
def show_frequency_response(filter_type: FilterType, samplerate: int) -> None:
"""
Show frequency response of a filter
>>> from audio_filters.iir_filter import IIRFilter
>>> filt = IIRFilter(4)
>>> show_frequency_response(filt, 48000)
"""
size = 512
inputs = [1] + [0] * (size - 1)
outputs = [filter_type.process(item) for item in inputs]
filler = [0] * (samplerate - size) # zero-padding
outputs += filler
fft_out = np.abs(np.fft.fft(outputs))
fft_db = 20 * np.log10(fft_out)
# Frequencies on log scale from 24 to nyquist frequency
plt.xlim(24, samplerate / 2 - 1)
plt.xlabel("Frequency (Hz)")
plt.xscale("log")
# Display within reasonable bounds
bounds = get_bounds(fft_db, samplerate)
plt.ylim(max([-80, bounds[0]]), min([80, bounds[1]]))
plt.ylabel("Gain (dB)")
plt.plot(fft_db)
plt.show()
def show_phase_response(filter_type: FilterType, samplerate: int) -> None:
"""
Show phase response of a filter
>>> from audio_filters.iir_filter import IIRFilter
>>> filt = IIRFilter(4)
>>> show_phase_response(filt, 48000)
"""
size = 512
inputs = [1] + [0] * (size - 1)
outputs = [filter_type.process(item) for item in inputs]
filler = [0] * (samplerate - size) # zero-padding
outputs += filler
fft_out = np.angle(np.fft.fft(outputs))
# Frequencies on log scale from 24 to nyquist frequency
plt.xlim(24, samplerate / 2 - 1)
plt.xlabel("Frequency (Hz)")
plt.xscale("log")
plt.ylim(-2 * pi, 2 * pi)
plt.ylabel("Phase shift (Radians)")
plt.plot(np.unwrap(fft_out, -2 * pi))
plt.show()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/audio_filters/__init__.py | audio_filters/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/audio_filters/butterworth_filter.py | audio_filters/butterworth_filter.py | from math import cos, sin, sqrt, tau
from audio_filters.iir_filter import IIRFilter
"""
Create 2nd-order IIR filters with Butterworth design.
Code based on https://webaudio.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html
Alternatively you can use scipy.signal.butter, which should yield the same results.
"""
def make_lowpass(
frequency: int,
samplerate: int,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a low-pass filter
>>> filter = make_lowpass(1000, 48000)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[1.0922959556412573, -1.9828897227476208, 0.9077040443587427, 0.004277569313094809,
0.008555138626189618, 0.004277569313094809]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
b0 = (1 - _cos) / 2
b1 = 1 - _cos
a0 = 1 + alpha
a1 = -2 * _cos
a2 = 1 - alpha
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b0])
return filt
def make_highpass(
frequency: int,
samplerate: int,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a high-pass filter
>>> filter = make_highpass(1000, 48000)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[1.0922959556412573, -1.9828897227476208, 0.9077040443587427, 0.9957224306869052,
-1.9914448613738105, 0.9957224306869052]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
b0 = (1 + _cos) / 2
b1 = -1 - _cos
a0 = 1 + alpha
a1 = -2 * _cos
a2 = 1 - alpha
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b0])
return filt
def make_bandpass(
frequency: int,
samplerate: int,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a band-pass filter
>>> filter = make_bandpass(1000, 48000)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[1.0922959556412573, -1.9828897227476208, 0.9077040443587427, 0.06526309611002579,
0, -0.06526309611002579]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
b0 = _sin / 2
b1 = 0
b2 = -b0
a0 = 1 + alpha
a1 = -2 * _cos
a2 = 1 - alpha
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b2])
return filt
def make_allpass(
frequency: int,
samplerate: int,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates an all-pass filter
>>> filter = make_allpass(1000, 48000)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[1.0922959556412573, -1.9828897227476208, 0.9077040443587427, 0.9077040443587427,
-1.9828897227476208, 1.0922959556412573]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
b0 = 1 - alpha
b1 = -2 * _cos
b2 = 1 + alpha
filt = IIRFilter(2)
filt.set_coefficients([b2, b1, b0], [b0, b1, b2])
return filt
def make_peak(
frequency: int,
samplerate: int,
gain_db: float,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a peak filter
>>> filter = make_peak(1000, 48000, 6)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[1.0653405327119334, -1.9828897227476208, 0.9346594672880666, 1.1303715025601122,
-1.9828897227476208, 0.8696284974398878]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
big_a = 10 ** (gain_db / 40)
b0 = 1 + alpha * big_a
b1 = -2 * _cos
b2 = 1 - alpha * big_a
a0 = 1 + alpha / big_a
a1 = -2 * _cos
a2 = 1 - alpha / big_a
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b2])
return filt
def make_lowshelf(
frequency: int,
samplerate: int,
gain_db: float,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a low-shelf filter
>>> filter = make_lowshelf(1000, 48000, 6)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[3.0409336710888786, -5.608870992220748, 2.602157875636628, 3.139954022810743,
-5.591841778072785, 2.5201667380627257]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
big_a = 10 ** (gain_db / 40)
pmc = (big_a + 1) - (big_a - 1) * _cos
ppmc = (big_a + 1) + (big_a - 1) * _cos
mpc = (big_a - 1) - (big_a + 1) * _cos
pmpc = (big_a - 1) + (big_a + 1) * _cos
aa2 = 2 * sqrt(big_a) * alpha
b0 = big_a * (pmc + aa2)
b1 = 2 * big_a * mpc
b2 = big_a * (pmc - aa2)
a0 = ppmc + aa2
a1 = -2 * pmpc
a2 = ppmc - aa2
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b2])
return filt
def make_highshelf(
frequency: int,
samplerate: int,
gain_db: float,
q_factor: float = 1 / sqrt(2),
) -> IIRFilter:
"""
Creates a high-shelf filter
>>> filter = make_highshelf(1000, 48000, 6)
>>> filter.a_coeffs + filter.b_coeffs # doctest: +NORMALIZE_WHITESPACE
[2.2229172136088806, -3.9587208137297303, 1.7841414181566304, 4.295432981120543,
-7.922740859457287, 3.6756456963725253]
"""
w0 = tau * frequency / samplerate
_sin = sin(w0)
_cos = cos(w0)
alpha = _sin / (2 * q_factor)
big_a = 10 ** (gain_db / 40)
pmc = (big_a + 1) - (big_a - 1) * _cos
ppmc = (big_a + 1) + (big_a - 1) * _cos
mpc = (big_a - 1) - (big_a + 1) * _cos
pmpc = (big_a - 1) + (big_a + 1) * _cos
aa2 = 2 * sqrt(big_a) * alpha
b0 = big_a * (ppmc + aa2)
b1 = -2 * big_a * pmpc
b2 = big_a * (ppmc - aa2)
a0 = pmc + aa2
a1 = 2 * mpc
a2 = pmc - aa2
filt = IIRFilter(2)
filt.set_coefficients([a0, a1, a2], [b0, b1, b2])
return filt
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/audio_filters/iir_filter.py | audio_filters/iir_filter.py | from __future__ import annotations
class IIRFilter:
r"""
N-Order IIR filter
Assumes working with float samples normalized on [-1, 1]
---
Implementation details:
Based on the 2nd-order function from
https://en.wikipedia.org/wiki/Digital_biquad_filter,
this generalized N-order function was made.
Using the following transfer function
.. math:: H(z)=\frac{b_{0}+b_{1}z^{-1}+b_{2}z^{-2}+...+b_{k}z^{-k}}
{a_{0}+a_{1}z^{-1}+a_{2}z^{-2}+...+a_{k}z^{-k}}
we can rewrite this to
.. math:: y[n]={\frac{1}{a_{0}}}
\left(\left(b_{0}x[n]+b_{1}x[n-1]+b_{2}x[n-2]+...+b_{k}x[n-k]\right)-
\left(a_{1}y[n-1]+a_{2}y[n-2]+...+a_{k}y[n-k]\right)\right)
"""
def __init__(self, order: int) -> None:
self.order = order
# a_{0} ... a_{k}
self.a_coeffs = [1.0] + [0.0] * order
# b_{0} ... b_{k}
self.b_coeffs = [1.0] + [0.0] * order
# x[n-1] ... x[n-k]
self.input_history = [0.0] * self.order
# y[n-1] ... y[n-k]
self.output_history = [0.0] * self.order
def set_coefficients(self, a_coeffs: list[float], b_coeffs: list[float]) -> None:
"""
Set the coefficients for the IIR filter.
These should both be of size `order` + 1.
:math:`a_0` may be left out, and it will use 1.0 as default value.
This method works well with scipy's filter design functions
>>> # Make a 2nd-order 1000Hz butterworth lowpass filter
>>> import scipy.signal
>>> b_coeffs, a_coeffs = scipy.signal.butter(2, 1000,
... btype='lowpass',
... fs=48000)
>>> filt = IIRFilter(2)
>>> filt.set_coefficients(a_coeffs, b_coeffs)
"""
if len(a_coeffs) < self.order:
a_coeffs = [1.0, *a_coeffs]
if len(a_coeffs) != self.order + 1:
msg = (
f"Expected a_coeffs to have {self.order + 1} elements "
f"for {self.order}-order filter, got {len(a_coeffs)}"
)
raise ValueError(msg)
if len(b_coeffs) != self.order + 1:
msg = (
f"Expected b_coeffs to have {self.order + 1} elements "
f"for {self.order}-order filter, got {len(a_coeffs)}"
)
raise ValueError(msg)
self.a_coeffs = a_coeffs
self.b_coeffs = b_coeffs
def process(self, sample: float) -> float:
"""
Calculate :math:`y[n]`
>>> filt = IIRFilter(2)
>>> filt.process(0)
0.0
"""
result = 0.0
# Start at index 1 and do index 0 at the end.
for i in range(1, self.order + 1):
result += (
self.b_coeffs[i] * self.input_history[i - 1]
- self.a_coeffs[i] * self.output_history[i - 1]
)
result = (result + self.b_coeffs[0] * sample) / self.a_coeffs[0]
self.input_history[1:] = self.input_history[:-1]
self.output_history[1:] = self.output_history[:-1]
self.input_history[0] = sample
self.output_history[0] = result
return result
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/test_digital_image_processing.py | digital_image_processing/test_digital_image_processing.py | """
PyTest's for Digital Image Processing
"""
import numpy as np
from cv2 import COLOR_BGR2GRAY, cvtColor, imread
from numpy import array, uint8
from PIL import Image
from digital_image_processing import change_contrast as cc
from digital_image_processing import convert_to_negative as cn
from digital_image_processing import sepia as sp
from digital_image_processing.dithering import burkes as bs
from digital_image_processing.edge_detection import canny
from digital_image_processing.filters import convolve as conv
from digital_image_processing.filters import gaussian_filter as gg
from digital_image_processing.filters import local_binary_pattern as lbp
from digital_image_processing.filters import median_filter as med
from digital_image_processing.filters import sobel_filter as sob
from digital_image_processing.resize import resize as rs
img = imread(r"digital_image_processing/image_data/lena_small.jpg")
gray = cvtColor(img, COLOR_BGR2GRAY)
# Test: convert_to_negative()
def test_convert_to_negative():
negative_img = cn.convert_to_negative(img)
# assert negative_img array for at least one True
assert negative_img.any()
# Test: change_contrast()
def test_change_contrast():
with Image.open("digital_image_processing/image_data/lena_small.jpg") as img:
# Work around assertion for response
assert str(cc.change_contrast(img, 110)).startswith(
"<PIL.Image.Image image mode=RGB size=100x100 at"
)
# canny.gen_gaussian_kernel()
def test_gen_gaussian_kernel():
resp = canny.gen_gaussian_kernel(9, sigma=1.4)
# Assert ambiguous array
assert resp.all()
# canny.py
def test_canny():
canny_img = imread("digital_image_processing/image_data/lena_small.jpg", 0)
# assert ambiguous array for all == True
assert canny_img.all()
canny_array = canny.canny(canny_img)
# assert canny array for at least one True
assert canny_array.any()
# filters/gaussian_filter.py
def test_gen_gaussian_kernel_filter():
assert gg.gaussian_filter(gray, 5, sigma=0.9).all()
def test_convolve_filter():
# laplace diagonals
laplace = array([[0.25, 0.5, 0.25], [0.5, -3, 0.5], [0.25, 0.5, 0.25]])
res = conv.img_convolve(gray, laplace).astype(uint8)
assert res.any()
def test_median_filter():
assert med.median_filter(gray, 3).any()
def test_sobel_filter():
grad, theta = sob.sobel_filter(gray)
assert grad.any()
assert theta.any()
def test_sepia():
sepia = sp.make_sepia(img, 20)
assert sepia.all()
def test_burkes(file_path: str = "digital_image_processing/image_data/lena_small.jpg"):
burkes = bs.Burkes(imread(file_path, 1), 120)
burkes.process()
assert burkes.output_img.any()
def test_nearest_neighbour(
file_path: str = "digital_image_processing/image_data/lena_small.jpg",
):
nn = rs.NearestNeighbour(imread(file_path, 1), 400, 200)
nn.process()
assert nn.output.any()
def test_local_binary_pattern():
# pull request 10161 before:
# "digital_image_processing/image_data/lena.jpg"
# after: "digital_image_processing/image_data/lena_small.jpg"
from os import getenv # Speed up our Continuous Integration tests
file_name = "lena_small.jpg" if getenv("CI") else "lena.jpg"
file_path = f"digital_image_processing/image_data/{file_name}"
# Reading the image and converting it to grayscale
image = imread(file_path, 0)
# Test for get_neighbors_pixel function() return not None
x_coordinate = 0
y_coordinate = 0
center = image[x_coordinate][y_coordinate]
neighbors_pixels = lbp.get_neighbors_pixel(
image, x_coordinate, y_coordinate, center
)
assert neighbors_pixels is not None
# Test for local_binary_pattern function()
# Create a numpy array as the same height and width of read image
lbp_image = np.zeros((image.shape[0], image.shape[1]))
# Iterating through the image and calculating the local binary pattern value
# for each pixel.
for i in range(image.shape[0]):
for j in range(image.shape[1]):
lbp_image[i][j] = lbp.local_binary_value(image, i, j)
assert lbp_image.any()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/change_brightness.py | digital_image_processing/change_brightness.py | from PIL import Image
def change_brightness(img: Image, level: float) -> Image:
"""
Change the brightness of a PIL Image to a given level.
"""
def brightness(c: int) -> float:
"""
Fundamental Transformation/Operation that'll be performed on
every bit.
"""
return 128 + level + (c - 128)
if not -255.0 <= level <= 255.0:
raise ValueError("level must be between -255.0 (black) and 255.0 (white)")
return img.point(brightness)
if __name__ == "__main__":
# Load image
with Image.open("image_data/lena.jpg") as img:
# Change brightness to 100
brigt_img = change_brightness(img, 100)
brigt_img.save("image_data/lena_brightness.png", format="png")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/change_contrast.py | digital_image_processing/change_contrast.py | """
Changing contrast with PIL
This algorithm is used in
https://noivce.pythonanywhere.com/ Python web app.
psf/black: True
ruff : True
"""
from PIL import Image
def change_contrast(img: Image, level: int) -> Image:
"""
Function to change contrast
"""
factor = (259 * (level + 255)) / (255 * (259 - level))
def contrast(c: int) -> int:
"""
Fundamental Transformation/Operation that'll be performed on
every bit.
"""
return int(128 + factor * (c - 128))
return img.point(contrast)
if __name__ == "__main__":
# Load image
with Image.open("image_data/lena.jpg") as img:
# Change contrast to 170
cont_img = change_contrast(img, 170)
cont_img.save("image_data/lena_high_contrast.png", format="png")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/__init__.py | digital_image_processing/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/sepia.py | digital_image_processing/sepia.py | """
Implemented an algorithm using opencv to tone an image with sepia technique
"""
from cv2 import destroyAllWindows, imread, imshow, waitKey
def make_sepia(img, factor: int):
"""
Function create sepia tone.
Source: https://en.wikipedia.org/wiki/Sepia_(color)
"""
pixel_h, pixel_v = img.shape[0], img.shape[1]
def to_grayscale(blue, green, red):
"""
Helper function to create pixel's greyscale representation
Src: https://pl.wikipedia.org/wiki/YUV
"""
return 0.2126 * red + 0.587 * green + 0.114 * blue
def normalize(value):
"""Helper function to normalize R/G/B value -> return 255 if value > 255"""
return min(value, 255)
for i in range(pixel_h):
for j in range(pixel_v):
greyscale = int(to_grayscale(*img[i][j]))
img[i][j] = [
normalize(greyscale),
normalize(greyscale + factor),
normalize(greyscale + 2 * factor),
]
return img
if __name__ == "__main__":
# read original image
images = {
percentage: imread("image_data/lena.jpg", 1) for percentage in (10, 20, 30, 40)
}
for percentage, img in images.items():
make_sepia(img, percentage)
for percentage, img in images.items():
imshow(f"Original image with sepia (factor: {percentage})", img)
waitKey(0)
destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/index_calculation.py | digital_image_processing/index_calculation.py | # Author: João Gustavo A. Amorim
# Author email: joaogustavoamorim@gmail.com
# Coding date: jan 2019
# python/black: True
# Imports
import numpy as np
# Class implemented to calculus the index
class IndexCalculation:
"""
# Class Summary
This algorithm consists in calculating vegetation indices, these
indices can be used for precision agriculture for example (or remote
sensing). There are functions to define the data and to calculate the
implemented indices.
# Vegetation index
https://en.wikipedia.org/wiki/Vegetation_Index
A Vegetation Index (VI) is a spectral transformation of two or more bands
designed to enhance the contribution of vegetation properties and allow
reliable spatial and temporal inter-comparisons of terrestrial
photosynthetic activity and canopy structural variations
# Information about channels (Wavelength range for each)
* nir - near-infrared
https://www.malvernpanalytical.com/br/products/technology/near-infrared-spectroscopy
Wavelength Range 700 nm to 2500 nm
* Red Edge
https://en.wikipedia.org/wiki/Red_edge
Wavelength Range 680 nm to 730 nm
* red
https://en.wikipedia.org/wiki/Color
Wavelength Range 635 nm to 700 nm
* blue
https://en.wikipedia.org/wiki/Color
Wavelength Range 450 nm to 490 nm
* green
https://en.wikipedia.org/wiki/Color
Wavelength Range 520 nm to 560 nm
# Implemented index list
#"abbreviationOfIndexName" -- list of channels used
#"ARVI2" -- red, nir
#"CCCI" -- red, redEdge, nir
#"CVI" -- red, green, nir
#"GLI" -- red, green, blue
#"NDVI" -- red, nir
#"BNDVI" -- blue, nir
#"redEdgeNDVI" -- red, redEdge
#"GNDVI" -- green, nir
#"GBNDVI" -- green, blue, nir
#"GRNDVI" -- red, green, nir
#"RBNDVI" -- red, blue, nir
#"PNDVI" -- red, green, blue, nir
#"ATSAVI" -- red, nir
#"BWDRVI" -- blue, nir
#"CIgreen" -- green, nir
#"CIrededge" -- redEdge, nir
#"CI" -- red, blue
#"CTVI" -- red, nir
#"GDVI" -- green, nir
#"EVI" -- red, blue, nir
#"GEMI" -- red, nir
#"GOSAVI" -- green, nir
#"GSAVI" -- green, nir
#"Hue" -- red, green, blue
#"IVI" -- red, nir
#"IPVI" -- red, nir
#"I" -- red, green, blue
#"RVI" -- red, nir
#"MRVI" -- red, nir
#"MSAVI" -- red, nir
#"NormG" -- red, green, nir
#"NormNIR" -- red, green, nir
#"NormR" -- red, green, nir
#"NGRDI" -- red, green
#"RI" -- red, green
#"S" -- red, green, blue
#"IF" -- red, green, blue
#"DVI" -- red, nir
#"TVI" -- red, nir
#"NDRE" -- redEdge, nir
#list of all index implemented
#allIndex = ["ARVI2", "CCCI", "CVI", "GLI", "NDVI", "BNDVI", "redEdgeNDVI",
"GNDVI", "GBNDVI", "GRNDVI", "RBNDVI", "PNDVI", "ATSAVI",
"BWDRVI", "CIgreen", "CIrededge", "CI", "CTVI", "GDVI", "EVI",
"GEMI", "GOSAVI", "GSAVI", "Hue", "IVI", "IPVI", "I", "RVI",
"MRVI", "MSAVI", "NormG", "NormNIR", "NormR", "NGRDI", "RI",
"S", "IF", "DVI", "TVI", "NDRE"]
#list of index with not blue channel
#notBlueIndex = ["ARVI2", "CCCI", "CVI", "NDVI", "redEdgeNDVI", "GNDVI",
"GRNDVI", "ATSAVI", "CIgreen", "CIrededge", "CTVI", "GDVI",
"GEMI", "GOSAVI", "GSAVI", "IVI", "IPVI", "RVI", "MRVI",
"MSAVI", "NormG", "NormNIR", "NormR", "NGRDI", "RI", "DVI",
"TVI", "NDRE"]
#list of index just with RGB channels
#RGBIndex = ["GLI", "CI", "Hue", "I", "NGRDI", "RI", "S", "IF"]
"""
def __init__(self, red=None, green=None, blue=None, red_edge=None, nir=None):
self.set_matricies(red=red, green=green, blue=blue, red_edge=red_edge, nir=nir)
def set_matricies(self, red=None, green=None, blue=None, red_edge=None, nir=None):
if red is not None:
self.red = red
if green is not None:
self.green = green
if blue is not None:
self.blue = blue
if red_edge is not None:
self.redEdge = red_edge
if nir is not None:
self.nir = nir
return True
def calculation(
self, index="", red=None, green=None, blue=None, red_edge=None, nir=None
):
"""
performs the calculation of the index with the values instantiated in the class
:str index: abbreviation of index name to perform
"""
self.set_matricies(red=red, green=green, blue=blue, red_edge=red_edge, nir=nir)
funcs = {
"ARVI2": self.arv12,
"CCCI": self.ccci,
"CVI": self.cvi,
"GLI": self.gli,
"NDVI": self.ndvi,
"BNDVI": self.bndvi,
"redEdgeNDVI": self.red_edge_ndvi,
"GNDVI": self.gndvi,
"GBNDVI": self.gbndvi,
"GRNDVI": self.grndvi,
"RBNDVI": self.rbndvi,
"PNDVI": self.pndvi,
"ATSAVI": self.atsavi,
"BWDRVI": self.bwdrvi,
"CIgreen": self.ci_green,
"CIrededge": self.ci_rededge,
"CI": self.ci,
"CTVI": self.ctvi,
"GDVI": self.gdvi,
"EVI": self.evi,
"GEMI": self.gemi,
"GOSAVI": self.gosavi,
"GSAVI": self.gsavi,
"Hue": self.hue,
"IVI": self.ivi,
"IPVI": self.ipvi,
"I": self.i,
"RVI": self.rvi,
"MRVI": self.mrvi,
"MSAVI": self.m_savi,
"NormG": self.norm_g,
"NormNIR": self.norm_nir,
"NormR": self.norm_r,
"NGRDI": self.ngrdi,
"RI": self.ri,
"S": self.s,
"IF": self._if,
"DVI": self.dvi,
"TVI": self.tvi,
"NDRE": self.ndre,
}
try:
return funcs[index]()
except KeyError:
print("Index not in the list!")
return False
def arv12(self):
"""
Atmospherically Resistant Vegetation Index 2
https://www.indexdatabase.de/db/i-single.php?id=396
:return: index
-0.18+1.17*(self.nir-self.red)/(self.nir+self.red)
"""
return -0.18 + (1.17 * ((self.nir - self.red) / (self.nir + self.red)))
def ccci(self):
"""
Canopy Chlorophyll Content Index
https://www.indexdatabase.de/db/i-single.php?id=224
:return: index
"""
return ((self.nir - self.redEdge) / (self.nir + self.redEdge)) / (
(self.nir - self.red) / (self.nir + self.red)
)
def cvi(self):
"""
Chlorophyll vegetation index
https://www.indexdatabase.de/db/i-single.php?id=391
:return: index
"""
return self.nir * (self.red / (self.green**2))
def gli(self):
"""
self.green leaf index
https://www.indexdatabase.de/db/i-single.php?id=375
:return: index
"""
return (2 * self.green - self.red - self.blue) / (
2 * self.green + self.red + self.blue
)
def ndvi(self):
"""
Normalized Difference self.nir/self.red Normalized Difference Vegetation
Index, Calibrated NDVI - CDVI
https://www.indexdatabase.de/db/i-single.php?id=58
:return: index
"""
return (self.nir - self.red) / (self.nir + self.red)
def bndvi(self):
"""
Normalized Difference self.nir/self.blue self.blue-normalized difference
vegetation index
https://www.indexdatabase.de/db/i-single.php?id=135
:return: index
"""
return (self.nir - self.blue) / (self.nir + self.blue)
def red_edge_ndvi(self):
"""
Normalized Difference self.rededge/self.red
https://www.indexdatabase.de/db/i-single.php?id=235
:return: index
"""
return (self.redEdge - self.red) / (self.redEdge + self.red)
def gndvi(self):
"""
Normalized Difference self.nir/self.green self.green NDVI
https://www.indexdatabase.de/db/i-single.php?id=401
:return: index
"""
return (self.nir - self.green) / (self.nir + self.green)
def gbndvi(self):
"""
self.green-self.blue NDVI
https://www.indexdatabase.de/db/i-single.php?id=186
:return: index
"""
return (self.nir - (self.green + self.blue)) / (
self.nir + (self.green + self.blue)
)
def grndvi(self):
"""
self.green-self.red NDVI
https://www.indexdatabase.de/db/i-single.php?id=185
:return: index
"""
return (self.nir - (self.green + self.red)) / (
self.nir + (self.green + self.red)
)
def rbndvi(self):
"""
self.red-self.blue NDVI
https://www.indexdatabase.de/db/i-single.php?id=187
:return: index
"""
return (self.nir - (self.blue + self.red)) / (self.nir + (self.blue + self.red))
def pndvi(self):
"""
Pan NDVI
https://www.indexdatabase.de/db/i-single.php?id=188
:return: index
"""
return (self.nir - (self.green + self.red + self.blue)) / (
self.nir + (self.green + self.red + self.blue)
)
def atsavi(self, x=0.08, a=1.22, b=0.03):
"""
Adjusted transformed soil-adjusted VI
https://www.indexdatabase.de/db/i-single.php?id=209
:return: index
"""
return a * (
(self.nir - a * self.red - b)
/ (a * self.nir + self.red - a * b + x * (1 + a**2))
)
def bwdrvi(self):
"""
self.blue-wide dynamic range vegetation index
https://www.indexdatabase.de/db/i-single.php?id=136
:return: index
"""
return (0.1 * self.nir - self.blue) / (0.1 * self.nir + self.blue)
def ci_green(self):
"""
Chlorophyll Index self.green
https://www.indexdatabase.de/db/i-single.php?id=128
:return: index
"""
return (self.nir / self.green) - 1
def ci_rededge(self):
"""
Chlorophyll Index self.redEdge
https://www.indexdatabase.de/db/i-single.php?id=131
:return: index
"""
return (self.nir / self.redEdge) - 1
def ci(self):
"""
Coloration Index
https://www.indexdatabase.de/db/i-single.php?id=11
:return: index
"""
return (self.red - self.blue) / self.red
def ctvi(self):
"""
Corrected Transformed Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=244
:return: index
"""
ndvi = self.ndvi()
return ((ndvi + 0.5) / (abs(ndvi + 0.5))) * (abs(ndvi + 0.5) ** (1 / 2))
def gdvi(self):
"""
Difference self.nir/self.green self.green Difference Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=27
:return: index
"""
return self.nir - self.green
def evi(self):
"""
Enhanced Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=16
:return: index
"""
return 2.5 * (
(self.nir - self.red) / (self.nir + 6 * self.red - 7.5 * self.blue + 1)
)
def gemi(self):
"""
Global Environment Monitoring Index
https://www.indexdatabase.de/db/i-single.php?id=25
:return: index
"""
n = (2 * (self.nir**2 - self.red**2) + 1.5 * self.nir + 0.5 * self.red) / (
self.nir + self.red + 0.5
)
return n * (1 - 0.25 * n) - (self.red - 0.125) / (1 - self.red)
def gosavi(self, y=0.16):
"""
self.green Optimized Soil Adjusted Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=29
mit Y = 0,16
:return: index
"""
return (self.nir - self.green) / (self.nir + self.green + y)
def gsavi(self, n=0.5):
"""
self.green Soil Adjusted Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=31
mit N = 0,5
:return: index
"""
return ((self.nir - self.green) / (self.nir + self.green + n)) * (1 + n)
def hue(self):
"""
Hue
https://www.indexdatabase.de/db/i-single.php?id=34
:return: index
"""
return np.arctan(
((2 * self.red - self.green - self.blue) / 30.5) * (self.green - self.blue)
)
def ivi(self, a=None, b=None):
"""
Ideal vegetation index
https://www.indexdatabase.de/db/i-single.php?id=276
b=intercept of vegetation line
a=soil line slope
:return: index
"""
return (self.nir - b) / (a * self.red)
def ipvi(self):
"""
Infraself.red percentage vegetation index
https://www.indexdatabase.de/db/i-single.php?id=35
:return: index
"""
return (self.nir / ((self.nir + self.red) / 2)) * (self.ndvi() + 1)
def i(self):
"""
Intensity
https://www.indexdatabase.de/db/i-single.php?id=36
:return: index
"""
return (self.red + self.green + self.blue) / 30.5
def rvi(self):
"""
Ratio-Vegetation-Index
http://www.seos-project.eu/modules/remotesensing/remotesensing-c03-s01-p01.html
:return: index
"""
return self.nir / self.red
def mrvi(self):
"""
Modified Normalized Difference Vegetation Index RVI
https://www.indexdatabase.de/db/i-single.php?id=275
:return: index
"""
return (self.rvi() - 1) / (self.rvi() + 1)
def m_savi(self):
"""
Modified Soil Adjusted Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=44
:return: index
"""
return (
(2 * self.nir + 1)
- ((2 * self.nir + 1) ** 2 - 8 * (self.nir - self.red)) ** (1 / 2)
) / 2
def norm_g(self):
"""
Norm G
https://www.indexdatabase.de/db/i-single.php?id=50
:return: index
"""
return self.green / (self.nir + self.red + self.green)
def norm_nir(self):
"""
Norm self.nir
https://www.indexdatabase.de/db/i-single.php?id=51
:return: index
"""
return self.nir / (self.nir + self.red + self.green)
def norm_r(self):
"""
Norm R
https://www.indexdatabase.de/db/i-single.php?id=52
:return: index
"""
return self.red / (self.nir + self.red + self.green)
def ngrdi(self):
"""
Normalized Difference self.green/self.red Normalized self.green self.red
difference index, Visible Atmospherically Resistant Indices self.green
(VIself.green)
https://www.indexdatabase.de/db/i-single.php?id=390
:return: index
"""
return (self.green - self.red) / (self.green + self.red)
def ri(self):
"""
Normalized Difference self.red/self.green self.redness Index
https://www.indexdatabase.de/db/i-single.php?id=74
:return: index
"""
return (self.red - self.green) / (self.red + self.green)
def s(self):
"""
Saturation
https://www.indexdatabase.de/db/i-single.php?id=77
:return: index
"""
max_value = np.max([np.max(self.red), np.max(self.green), np.max(self.blue)])
min_value = np.min([np.min(self.red), np.min(self.green), np.min(self.blue)])
return (max_value - min_value) / max_value
def _if(self):
"""
Shape Index
https://www.indexdatabase.de/db/i-single.php?id=79
:return: index
"""
return (2 * self.red - self.green - self.blue) / (self.green - self.blue)
def dvi(self):
"""
Simple Ratio self.nir/self.red Difference Vegetation Index, Vegetation Index
Number (VIN)
https://www.indexdatabase.de/db/i-single.php?id=12
:return: index
"""
return self.nir / self.red
def tvi(self):
"""
Transformed Vegetation Index
https://www.indexdatabase.de/db/i-single.php?id=98
:return: index
"""
return (self.ndvi() + 0.5) ** (1 / 2)
def ndre(self):
return (self.nir - self.redEdge) / (self.nir + self.redEdge)
"""
# genering a random matrices to test this class
red = np.ones((1000,1000, 1),dtype="float64") * 46787
green = np.ones((1000,1000, 1),dtype="float64") * 23487
blue = np.ones((1000,1000, 1),dtype="float64") * 14578
redEdge = np.ones((1000,1000, 1),dtype="float64") * 51045
nir = np.ones((1000,1000, 1),dtype="float64") * 52200
# Examples of how to use the class
# instantiating the class
cl = IndexCalculation()
# instantiating the class with the values
#cl = indexCalculation(red=red, green=green, blue=blue, redEdge=redEdge, nir=nir)
# how set the values after instantiate the class cl, (for update the data or when don't
# instantiating the class with the values)
cl.setMatrices(red=red, green=green, blue=blue, redEdge=redEdge, nir=nir)
# calculating the indices for the instantiated values in the class
# Note: the CCCI index can be changed to any index implemented in the class.
indexValue_form1 = cl.calculation("CCCI", red=red, green=green, blue=blue,
redEdge=redEdge, nir=nir).astype(np.float64)
indexValue_form2 = cl.CCCI()
# calculating the index with the values directly -- you can set just the values
# preferred note: the *calculation* function performs the function *setMatrices*
indexValue_form3 = cl.calculation("CCCI", red=red, green=green, blue=blue,
redEdge=redEdge, nir=nir).astype(np.float64)
print("Form 1: "+np.array2string(indexValue_form1, precision=20, separator=', ',
floatmode='maxprec_equal'))
print("Form 2: "+np.array2string(indexValue_form2, precision=20, separator=', ',
floatmode='maxprec_equal'))
print("Form 3: "+np.array2string(indexValue_form3, precision=20, separator=', ',
floatmode='maxprec_equal'))
# A list of examples results for different type of data at NDVI
# float16 -> 0.31567383 #NDVI (red = 50, nir = 100)
# float32 -> 0.31578946 #NDVI (red = 50, nir = 100)
# float64 -> 0.3157894736842105 #NDVI (red = 50, nir = 100)
# longdouble -> 0.3157894736842105 #NDVI (red = 50, nir = 100)
"""
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/convert_to_negative.py | digital_image_processing/convert_to_negative.py | """
Implemented an algorithm using opencv to convert a colored image into its negative
"""
from cv2 import destroyAllWindows, imread, imshow, waitKey
def convert_to_negative(img):
# getting number of pixels in the image
pixel_h, pixel_v = img.shape[0], img.shape[1]
# converting each pixel's color to its negative
for i in range(pixel_h):
for j in range(pixel_v):
img[i][j] = [255, 255, 255] - img[i][j]
return img
if __name__ == "__main__":
# read original image
img = imread("image_data/lena.jpg", 1)
# convert to its negative
neg = convert_to_negative(img)
# show result image
imshow("negative of original image", img)
waitKey(0)
destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/histogram_equalization/histogram_stretch.py | digital_image_processing/histogram_equalization/histogram_stretch.py | """
Created on Fri Sep 28 15:22:29 2018
@author: Binish125
"""
import copy
import os
import cv2
import numpy as np
from matplotlib import pyplot as plt
class ConstantStretch:
def __init__(self):
self.img = ""
self.original_image = ""
self.last_list = []
self.rem = 0
self.L = 256
self.sk = 0
self.k = 0
self.number_of_rows = 0
self.number_of_cols = 0
def stretch(self, input_image):
self.img = cv2.imread(input_image, 0)
self.original_image = copy.deepcopy(self.img)
x, _, _ = plt.hist(self.img.ravel(), 256, [0, 256], label="x")
self.k = np.sum(x)
for i in range(len(x)):
prk = x[i] / self.k
self.sk += prk
last = (self.L - 1) * self.sk
if self.rem != 0:
self.rem = int(last % last)
last = int(last + 1 if self.rem >= 0.5 else last)
self.last_list.append(last)
self.number_of_rows = int(np.ma.count(self.img) / self.img[1].size)
self.number_of_cols = self.img[1].size
for i in range(self.number_of_cols):
for j in range(self.number_of_rows):
num = self.img[j][i]
if num != self.last_list[num]:
self.img[j][i] = self.last_list[num]
cv2.imwrite("output_data/output.jpg", self.img)
def plot_histogram(self):
plt.hist(self.img.ravel(), 256, [0, 256])
def show_image(self):
cv2.imshow("Output-Image", self.img)
cv2.imshow("Input-Image", self.original_image)
cv2.waitKey(5000)
cv2.destroyAllWindows()
if __name__ == "__main__":
file_path = os.path.join(os.path.basename(__file__), "image_data/input.jpg")
stretcher = ConstantStretch()
stretcher.stretch(file_path)
stretcher.plot_histogram()
stretcher.show_image()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/histogram_equalization/__init__.py | digital_image_processing/histogram_equalization/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/histogram_equalization/image_data/__init__.py | digital_image_processing/histogram_equalization/image_data/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/histogram_equalization/output_data/__init__.py | digital_image_processing/histogram_equalization/output_data/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/image_data/__init__.py | digital_image_processing/image_data/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/resize/resize.py | digital_image_processing/resize/resize.py | """Multiple image resizing techniques"""
import numpy as np
from cv2 import destroyAllWindows, imread, imshow, waitKey
class NearestNeighbour:
"""
Simplest and fastest version of image resizing.
Source: https://en.wikipedia.org/wiki/Nearest-neighbor_interpolation
"""
def __init__(self, img, dst_width: int, dst_height: int):
if dst_width < 0 or dst_height < 0:
raise ValueError("Destination width/height should be > 0")
self.img = img
self.src_w = img.shape[1]
self.src_h = img.shape[0]
self.dst_w = dst_width
self.dst_h = dst_height
self.ratio_x = self.src_w / self.dst_w
self.ratio_y = self.src_h / self.dst_h
self.output = self.output_img = (
np.ones((self.dst_h, self.dst_w, 3), np.uint8) * 255
)
def process(self):
for i in range(self.dst_h):
for j in range(self.dst_w):
self.output[i][j] = self.img[self.get_y(i)][self.get_x(j)]
def get_x(self, x: int) -> int:
"""
Get parent X coordinate for destination X
:param x: Destination X coordinate
:return: Parent X coordinate based on `x ratio`
>>> nn = NearestNeighbour(imread("digital_image_processing/image_data/lena.jpg",
... 1), 100, 100)
>>> nn.ratio_x = 0.5
>>> nn.get_x(4)
2
"""
return int(self.ratio_x * x)
def get_y(self, y: int) -> int:
"""
Get parent Y coordinate for destination Y
:param y: Destination X coordinate
:return: Parent X coordinate based on `y ratio`
>>> nn = NearestNeighbour(imread("digital_image_processing/image_data/lena.jpg",
... 1), 100, 100)
>>> nn.ratio_y = 0.5
>>> nn.get_y(4)
2
"""
return int(self.ratio_y * y)
if __name__ == "__main__":
dst_w, dst_h = 800, 600
im = imread("image_data/lena.jpg", 1)
n = NearestNeighbour(im, dst_w, dst_h)
n.process()
imshow(
f"Image resized from: {im.shape[1]}x{im.shape[0]} to {dst_w}x{dst_h}", n.output
)
waitKey(0)
destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/resize/__init__.py | digital_image_processing/resize/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/gaussian_filter.py | digital_image_processing/filters/gaussian_filter.py | """
Implementation of gaussian filter algorithm
"""
from itertools import product
from cv2 import COLOR_BGR2GRAY, cvtColor, imread, imshow, waitKey
from numpy import dot, exp, mgrid, pi, ravel, square, uint8, zeros
def gen_gaussian_kernel(k_size, sigma):
center = k_size // 2
x, y = mgrid[0 - center : k_size - center, 0 - center : k_size - center]
g = 1 / (2 * pi * sigma) * exp(-(square(x) + square(y)) / (2 * square(sigma)))
return g
def gaussian_filter(image, k_size, sigma):
height, width = image.shape[0], image.shape[1]
# dst image height and width
dst_height = height - k_size + 1
dst_width = width - k_size + 1
# im2col, turn the k_size*k_size pixels into a row and np.vstack all rows
image_array = zeros((dst_height * dst_width, k_size * k_size))
for row, (i, j) in enumerate(product(range(dst_height), range(dst_width))):
window = ravel(image[i : i + k_size, j : j + k_size])
image_array[row, :] = window
# turn the kernel into shape(k*k, 1)
gaussian_kernel = gen_gaussian_kernel(k_size, sigma)
filter_array = ravel(gaussian_kernel)
# reshape and get the dst image
dst = dot(image_array, filter_array).reshape(dst_height, dst_width).astype(uint8)
return dst
if __name__ == "__main__":
# read original image
img = imread(r"../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
# get values with two different mask size
gaussian3x3 = gaussian_filter(gray, 3, sigma=1)
gaussian5x5 = gaussian_filter(gray, 5, sigma=0.8)
# show result images
imshow("gaussian filter with 3x3 mask", gaussian3x3)
imshow("gaussian filter with 5x5 mask", gaussian5x5)
waitKey()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/sobel_filter.py | digital_image_processing/filters/sobel_filter.py | # @Author : lightXu
# @File : sobel_filter.py
# @Time : 2019/7/8 0008 下午 16:26
import numpy as np
from cv2 import COLOR_BGR2GRAY, cvtColor, imread, imshow, waitKey
from digital_image_processing.filters.convolve import img_convolve
def sobel_filter(image):
kernel_x = np.array([[-1, 0, 1], [-2, 0, 2], [-1, 0, 1]])
kernel_y = np.array([[1, 2, 1], [0, 0, 0], [-1, -2, -1]])
dst_x = np.abs(img_convolve(image, kernel_x))
dst_y = np.abs(img_convolve(image, kernel_y))
# modify the pix within [0, 255]
dst_x = dst_x * 255 / np.max(dst_x)
dst_y = dst_y * 255 / np.max(dst_y)
dst_xy = np.sqrt((np.square(dst_x)) + (np.square(dst_y)))
dst_xy = dst_xy * 255 / np.max(dst_xy)
dst = dst_xy.astype(np.uint8)
theta = np.arctan2(dst_y, dst_x)
return dst, theta
if __name__ == "__main__":
# read original image
img = imread("../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
sobel_grad, sobel_theta = sobel_filter(gray)
# show result images
imshow("sobel filter", sobel_grad)
imshow("sobel theta", sobel_theta)
waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/convolve.py | digital_image_processing/filters/convolve.py | # @Author : lightXu
# @File : convolve.py
# @Time : 2019/7/8 0008 下午 16:13
from cv2 import COLOR_BGR2GRAY, cvtColor, imread, imshow, waitKey
from numpy import array, dot, pad, ravel, uint8, zeros
def im2col(image, block_size):
rows, cols = image.shape
dst_height = cols - block_size[1] + 1
dst_width = rows - block_size[0] + 1
image_array = zeros((dst_height * dst_width, block_size[1] * block_size[0]))
row = 0
for i in range(dst_height):
for j in range(dst_width):
window = ravel(image[i : i + block_size[0], j : j + block_size[1]])
image_array[row, :] = window
row += 1
return image_array
def img_convolve(image, filter_kernel):
height, width = image.shape[0], image.shape[1]
k_size = filter_kernel.shape[0]
pad_size = k_size // 2
# Pads image with the edge values of array.
image_tmp = pad(image, pad_size, mode="edge")
# im2col, turn the k_size*k_size pixels into a row and np.vstack all rows
image_array = im2col(image_tmp, (k_size, k_size))
# turn the kernel into shape(k*k, 1)
kernel_array = ravel(filter_kernel)
# reshape and get the dst image
dst = dot(image_array, kernel_array).reshape(height, width)
return dst
if __name__ == "__main__":
# read original image
img = imread(r"../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
# Laplace operator
Laplace_kernel = array([[0, 1, 0], [1, -4, 1], [0, 1, 0]])
out = img_convolve(gray, Laplace_kernel).astype(uint8)
imshow("Laplacian", out)
waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/local_binary_pattern.py | digital_image_processing/filters/local_binary_pattern.py | import cv2
import numpy as np
def get_neighbors_pixel(
image: np.ndarray, x_coordinate: int, y_coordinate: int, center: int
) -> int:
"""
Comparing local neighborhood pixel value with threshold value of centre pixel.
Exception is required when neighborhood value of a center pixel value is null.
i.e. values present at boundaries.
:param image: The image we're working with
:param x_coordinate: x-coordinate of the pixel
:param y_coordinate: The y coordinate of the pixel
:param center: center pixel value
:return: The value of the pixel is being returned.
"""
try:
return int(image[x_coordinate][y_coordinate] >= center)
except (IndexError, TypeError):
return 0
def local_binary_value(image: np.ndarray, x_coordinate: int, y_coordinate: int) -> int:
"""
It takes an image, an x and y coordinate, and returns the
decimal value of the local binary patternof the pixel
at that coordinate
:param image: the image to be processed
:param x_coordinate: x coordinate of the pixel
:param y_coordinate: the y coordinate of the pixel
:return: The decimal value of the binary value of the pixels
around the center pixel.
"""
center = image[x_coordinate][y_coordinate]
powers = [1, 2, 4, 8, 16, 32, 64, 128]
# skip get_neighbors_pixel if center is null
if center is None:
return 0
# Starting from the top right, assigning value to pixels clockwise
binary_values = [
get_neighbors_pixel(image, x_coordinate - 1, y_coordinate + 1, center),
get_neighbors_pixel(image, x_coordinate, y_coordinate + 1, center),
get_neighbors_pixel(image, x_coordinate - 1, y_coordinate, center),
get_neighbors_pixel(image, x_coordinate + 1, y_coordinate + 1, center),
get_neighbors_pixel(image, x_coordinate + 1, y_coordinate, center),
get_neighbors_pixel(image, x_coordinate + 1, y_coordinate - 1, center),
get_neighbors_pixel(image, x_coordinate, y_coordinate - 1, center),
get_neighbors_pixel(image, x_coordinate - 1, y_coordinate - 1, center),
]
# Converting the binary value to decimal.
return sum(
binary_value * power for binary_value, power in zip(binary_values, powers)
)
if __name__ == "__main__":
# Reading the image and converting it to grayscale.
image = cv2.imread(
"digital_image_processing/image_data/lena.jpg", cv2.IMREAD_GRAYSCALE
)
# Create a numpy array as the same height and width of read image
lbp_image = np.zeros((image.shape[0], image.shape[1]))
# Iterating through the image and calculating the
# local binary pattern value for each pixel.
for i in range(image.shape[0]):
for j in range(image.shape[1]):
lbp_image[i][j] = local_binary_value(image, i, j)
cv2.imshow("local binary pattern", lbp_image)
cv2.waitKey(0)
cv2.destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/__init__.py | digital_image_processing/filters/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/median_filter.py | digital_image_processing/filters/median_filter.py | """
Implementation of median filter algorithm
"""
from cv2 import COLOR_BGR2GRAY, cvtColor, imread, imshow, waitKey
from numpy import divide, int8, multiply, ravel, sort, zeros_like
def median_filter(gray_img, mask=3):
"""
:param gray_img: gray image
:param mask: mask size
:return: image with median filter
"""
# set image borders
bd = int(mask / 2)
# copy image size
median_img = zeros_like(gray_img)
for i in range(bd, gray_img.shape[0] - bd):
for j in range(bd, gray_img.shape[1] - bd):
# get mask according with mask
kernel = ravel(gray_img[i - bd : i + bd + 1, j - bd : j + bd + 1])
# calculate mask median
median = sort(kernel)[int8(divide((multiply(mask, mask)), 2) + 1)]
median_img[i, j] = median
return median_img
if __name__ == "__main__":
# read original image
img = imread("../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
# get values with two different mask size
median3x3 = median_filter(gray, 3)
median5x5 = median_filter(gray, 5)
# show result images
imshow("median filter with 3x3 mask", median3x3)
imshow("median filter with 5x5 mask", median5x5)
waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/laplacian_filter.py | digital_image_processing/filters/laplacian_filter.py | # @Author : ojas-wani
# @File : laplacian_filter.py
# @Date : 10/04/2023
import numpy as np
from cv2 import (
BORDER_DEFAULT,
COLOR_BGR2GRAY,
CV_64F,
cvtColor,
filter2D,
imread,
imshow,
waitKey,
)
from digital_image_processing.filters.gaussian_filter import gaussian_filter
def my_laplacian(src: np.ndarray, ksize: int) -> np.ndarray:
"""
:param src: the source image, which should be a grayscale or color image.
:param ksize: the size of the kernel used to compute the Laplacian filter,
which can be 1, 3, 5, or 7.
>>> my_laplacian(src=np.array([]), ksize=0)
Traceback (most recent call last):
...
ValueError: ksize must be in (1, 3, 5, 7)
"""
kernels = {
1: np.array([[0, -1, 0], [-1, 4, -1], [0, -1, 0]]),
3: np.array([[0, 1, 0], [1, -4, 1], [0, 1, 0]]),
5: np.array(
[
[0, 0, -1, 0, 0],
[0, -1, -2, -1, 0],
[-1, -2, 16, -2, -1],
[0, -1, -2, -1, 0],
[0, 0, -1, 0, 0],
]
),
7: np.array(
[
[0, 0, 0, -1, 0, 0, 0],
[0, 0, -2, -3, -2, 0, 0],
[0, -2, -7, -10, -7, -2, 0],
[-1, -3, -10, 68, -10, -3, -1],
[0, -2, -7, -10, -7, -2, 0],
[0, 0, -2, -3, -2, 0, 0],
[0, 0, 0, -1, 0, 0, 0],
]
),
}
if ksize not in kernels:
msg = f"ksize must be in {tuple(kernels)}"
raise ValueError(msg)
# Apply the Laplacian kernel using convolution
return filter2D(
src, CV_64F, kernels[ksize], 0, borderType=BORDER_DEFAULT, anchor=(0, 0)
)
if __name__ == "__main__":
# read original image
img = imread(r"../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
# Applying gaussian filter
blur_image = gaussian_filter(gray, 3, sigma=1)
# Apply multiple Kernel to detect edges
laplacian_image = my_laplacian(ksize=3, src=blur_image)
imshow("Original image", img)
imshow("Detected edges using laplacian filter", laplacian_image)
waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/bilateral_filter.py | digital_image_processing/filters/bilateral_filter.py | """
Implementation of Bilateral filter
Inputs:
img: A 2d image with values in between 0 and 1
varS: variance in space dimension.
varI: variance in Intensity.
N: Kernel size(Must be an odd number)
Output:
img:A 2d zero padded image with values in between 0 and 1
"""
import math
import sys
import cv2
import numpy as np
def vec_gaussian(img: np.ndarray, variance: float) -> np.ndarray:
# For applying gaussian function for each element in matrix.
sigma = math.sqrt(variance)
cons = 1 / (sigma * math.sqrt(2 * math.pi))
return cons * np.exp(-((img / sigma) ** 2) * 0.5)
def get_slice(img: np.ndarray, x: int, y: int, kernel_size: int) -> np.ndarray:
half = kernel_size // 2
return img[x - half : x + half + 1, y - half : y + half + 1]
def get_gauss_kernel(kernel_size: int, spatial_variance: float) -> np.ndarray:
# Creates a gaussian kernel of given dimension.
arr = np.zeros((kernel_size, kernel_size))
for i in range(kernel_size):
for j in range(kernel_size):
arr[i, j] = math.sqrt(
abs(i - kernel_size // 2) ** 2 + abs(j - kernel_size // 2) ** 2
)
return vec_gaussian(arr, spatial_variance)
def bilateral_filter(
img: np.ndarray,
spatial_variance: float,
intensity_variance: float,
kernel_size: int,
) -> np.ndarray:
img2 = np.zeros(img.shape)
gauss_ker = get_gauss_kernel(kernel_size, spatial_variance)
size_x, size_y = img.shape
for i in range(kernel_size // 2, size_x - kernel_size // 2):
for j in range(kernel_size // 2, size_y - kernel_size // 2):
img_s = get_slice(img, i, j, kernel_size)
img_i = img_s - img_s[kernel_size // 2, kernel_size // 2]
img_ig = vec_gaussian(img_i, intensity_variance)
weights = np.multiply(gauss_ker, img_ig)
vals = np.multiply(img_s, weights)
val = np.sum(vals) / np.sum(weights)
img2[i, j] = val
return img2
def parse_args(args: list) -> tuple:
filename = args[1] if args[1:] else "../image_data/lena.jpg"
spatial_variance = float(args[2]) if args[2:] else 1.0
intensity_variance = float(args[3]) if args[3:] else 1.0
if args[4:]:
kernel_size = int(args[4])
kernel_size = kernel_size + abs(kernel_size % 2 - 1)
else:
kernel_size = 5
return filename, spatial_variance, intensity_variance, kernel_size
if __name__ == "__main__":
filename, spatial_variance, intensity_variance, kernel_size = parse_args(sys.argv)
img = cv2.imread(filename, 0)
cv2.imshow("input image", img)
out = img / 255
out = out.astype("float32")
out = bilateral_filter(out, spatial_variance, intensity_variance, kernel_size)
out = out * 255
out = np.uint8(out)
cv2.imshow("output image", out)
cv2.waitKey(0)
cv2.destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/filters/gabor_filter.py | digital_image_processing/filters/gabor_filter.py | # Implementation of the Gaborfilter
# https://en.wikipedia.org/wiki/Gabor_filter
import numpy as np
from cv2 import COLOR_BGR2GRAY, CV_8UC3, cvtColor, filter2D, imread, imshow, waitKey
def gabor_filter_kernel(
ksize: int, sigma: int, theta: int, lambd: int, gamma: int, psi: int
) -> np.ndarray:
"""
:param ksize: The kernelsize of the convolutional filter (ksize x ksize)
:param sigma: standard deviation of the gaussian bell curve
:param theta: The orientation of the normal to the parallel stripes
of Gabor function.
:param lambd: Wavelength of the sinusoidal component.
:param gamma: The spatial aspect ratio and specifies the ellipticity
of the support of Gabor function.
:param psi: The phase offset of the sinusoidal function.
>>> gabor_filter_kernel(3, 8, 0, 10, 0, 0).tolist()
[[0.8027212023735046, 1.0, 0.8027212023735046], [0.8027212023735046, 1.0, \
0.8027212023735046], [0.8027212023735046, 1.0, 0.8027212023735046]]
"""
# prepare kernel
# the kernel size have to be odd
if (ksize % 2) == 0:
ksize = ksize + 1
gabor = np.zeros((ksize, ksize), dtype=np.float32)
# each value
for y in range(ksize):
for x in range(ksize):
# distance from center
px = x - ksize // 2
py = y - ksize // 2
# degree to radiant
_theta = theta / 180 * np.pi
cos_theta = np.cos(_theta)
sin_theta = np.sin(_theta)
# get kernel x
_x = cos_theta * px + sin_theta * py
# get kernel y
_y = -sin_theta * px + cos_theta * py
# fill kernel
gabor[y, x] = np.exp(-(_x**2 + gamma**2 * _y**2) / (2 * sigma**2)) * np.cos(
2 * np.pi * _x / lambd + psi
)
return gabor
if __name__ == "__main__":
import doctest
doctest.testmod()
# read original image
img = imread("../image_data/lena.jpg")
# turn image in gray scale value
gray = cvtColor(img, COLOR_BGR2GRAY)
# Apply multiple Kernel to detect edges
out = np.zeros(gray.shape[:2])
for theta in [0, 30, 60, 90, 120, 150]:
"""
ksize = 10
sigma = 8
lambd = 10
gamma = 0
psi = 0
"""
kernel_10 = gabor_filter_kernel(10, 8, theta, 10, 0, 0)
out += filter2D(gray, CV_8UC3, kernel_10)
out = out / out.max() * 255
out = out.astype(np.uint8)
imshow("Original", gray)
imshow("Gabor filter with 20x20 mask and 6 directions", out)
waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/morphological_operations/dilation_operation.py | digital_image_processing/morphological_operations/dilation_operation.py | from pathlib import Path
import numpy as np
from PIL import Image
def rgb_to_gray(rgb: np.ndarray) -> np.ndarray:
"""
Return gray image from rgb image
>>> rgb_to_gray(np.array([[[127, 255, 0]]]))
array([[187.6453]])
>>> rgb_to_gray(np.array([[[0, 0, 0]]]))
array([[0.]])
>>> rgb_to_gray(np.array([[[2, 4, 1]]]))
array([[3.0598]])
>>> rgb_to_gray(np.array([[[26, 255, 14], [5, 147, 20], [1, 200, 0]]]))
array([[159.0524, 90.0635, 117.6989]])
"""
r, g, b = rgb[:, :, 0], rgb[:, :, 1], rgb[:, :, 2]
return 0.2989 * r + 0.5870 * g + 0.1140 * b
def gray_to_binary(gray: np.ndarray) -> np.ndarray:
"""
Return binary image from gray image
>>> gray_to_binary(np.array([[127, 255, 0]]))
array([[False, True, False]])
>>> gray_to_binary(np.array([[0]]))
array([[False]])
>>> gray_to_binary(np.array([[26.2409, 4.9315, 1.4729]]))
array([[False, False, False]])
>>> gray_to_binary(np.array([[26, 255, 14], [5, 147, 20], [1, 200, 0]]))
array([[False, True, False],
[False, True, False],
[False, True, False]])
"""
return (gray > 127) & (gray <= 255)
def dilation(image: np.ndarray, kernel: np.ndarray) -> np.ndarray:
"""
Return dilated image
>>> dilation(np.array([[True, False, True]]), np.array([[0, 1, 0]]))
array([[False, False, False]])
>>> dilation(np.array([[False, False, True]]), np.array([[1, 0, 1]]))
array([[False, False, False]])
"""
output = np.zeros_like(image)
image_padded = np.zeros(
(image.shape[0] + kernel.shape[0] - 1, image.shape[1] + kernel.shape[1] - 1)
)
# Copy image to padded image
image_padded[kernel.shape[0] - 2 : -1 :, kernel.shape[1] - 2 : -1 :] = image
# Iterate over image & apply kernel
for x in range(image.shape[1]):
for y in range(image.shape[0]):
summation = (
kernel * image_padded[y : y + kernel.shape[0], x : x + kernel.shape[1]]
).sum()
output[y, x] = int(summation > 0)
return output
if __name__ == "__main__":
# read original image
lena_path = Path(__file__).resolve().parent / "image_data" / "lena.jpg"
lena = np.array(Image.open(lena_path))
# kernel to be applied
structuring_element = np.array([[0, 1, 0], [1, 1, 1], [0, 1, 0]])
output = dilation(gray_to_binary(rgb_to_gray(lena)), structuring_element)
# Save the output image
pil_img = Image.fromarray(output).convert("RGB")
pil_img.save("result_dilation.png")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/morphological_operations/erosion_operation.py | digital_image_processing/morphological_operations/erosion_operation.py | from pathlib import Path
import numpy as np
from PIL import Image
def rgb_to_gray(rgb: np.ndarray) -> np.ndarray:
"""
Return gray image from rgb image
>>> rgb_to_gray(np.array([[[127, 255, 0]]]))
array([[187.6453]])
>>> rgb_to_gray(np.array([[[0, 0, 0]]]))
array([[0.]])
>>> rgb_to_gray(np.array([[[2, 4, 1]]]))
array([[3.0598]])
>>> rgb_to_gray(np.array([[[26, 255, 14], [5, 147, 20], [1, 200, 0]]]))
array([[159.0524, 90.0635, 117.6989]])
"""
r, g, b = rgb[:, :, 0], rgb[:, :, 1], rgb[:, :, 2]
return 0.2989 * r + 0.5870 * g + 0.1140 * b
def gray_to_binary(gray: np.ndarray) -> np.ndarray:
"""
Return binary image from gray image
>>> gray_to_binary(np.array([[127, 255, 0]]))
array([[False, True, False]])
>>> gray_to_binary(np.array([[0]]))
array([[False]])
>>> gray_to_binary(np.array([[26.2409, 4.9315, 1.4729]]))
array([[False, False, False]])
>>> gray_to_binary(np.array([[26, 255, 14], [5, 147, 20], [1, 200, 0]]))
array([[False, True, False],
[False, True, False],
[False, True, False]])
"""
return (gray > 127) & (gray <= 255)
def erosion(image: np.ndarray, kernel: np.ndarray) -> np.ndarray:
"""
Return eroded image
>>> erosion(np.array([[True, True, False]]), np.array([[0, 1, 0]]))
array([[False, False, False]])
>>> erosion(np.array([[True, False, False]]), np.array([[1, 1, 0]]))
array([[False, False, False]])
"""
output = np.zeros_like(image)
image_padded = np.zeros(
(image.shape[0] + kernel.shape[0] - 1, image.shape[1] + kernel.shape[1] - 1)
)
# Copy image to padded image
image_padded[kernel.shape[0] - 2 : -1 :, kernel.shape[1] - 2 : -1 :] = image
# Iterate over image & apply kernel
for x in range(image.shape[1]):
for y in range(image.shape[0]):
summation = (
kernel * image_padded[y : y + kernel.shape[0], x : x + kernel.shape[1]]
).sum()
output[y, x] = int(summation == 5)
return output
if __name__ == "__main__":
# read original image
lena_path = Path(__file__).resolve().parent / "image_data" / "lena.jpg"
lena = np.array(Image.open(lena_path))
# kernel to be applied
structuring_element = np.array([[0, 1, 0], [1, 1, 1], [0, 1, 0]])
# Apply erosion operation to a binary image
output = erosion(gray_to_binary(rgb_to_gray(lena)), structuring_element)
# Save the output image
pil_img = Image.fromarray(output).convert("RGB")
pil_img.save("result_erosion.png")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/morphological_operations/__init__.py | digital_image_processing/morphological_operations/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/edge_detection/canny.py | digital_image_processing/edge_detection/canny.py | import cv2
import numpy as np
from digital_image_processing.filters.convolve import img_convolve
from digital_image_processing.filters.sobel_filter import sobel_filter
PI = 180
def gen_gaussian_kernel(k_size, sigma):
center = k_size // 2
x, y = np.mgrid[0 - center : k_size - center, 0 - center : k_size - center]
g = (
1
/ (2 * np.pi * sigma)
* np.exp(-(np.square(x) + np.square(y)) / (2 * np.square(sigma)))
)
return g
def suppress_non_maximum(image_shape, gradient_direction, sobel_grad):
"""
Non-maximum suppression. If the edge strength of the current pixel is the largest
compared to the other pixels in the mask with the same direction, the value will be
preserved. Otherwise, the value will be suppressed.
"""
destination = np.zeros(image_shape)
for row in range(1, image_shape[0] - 1):
for col in range(1, image_shape[1] - 1):
direction = gradient_direction[row, col]
if (
0 <= direction < PI / 8
or 15 * PI / 8 <= direction <= 2 * PI
or 7 * PI / 8 <= direction <= 9 * PI / 8
):
w = sobel_grad[row, col - 1]
e = sobel_grad[row, col + 1]
if sobel_grad[row, col] >= w and sobel_grad[row, col] >= e:
destination[row, col] = sobel_grad[row, col]
elif (
PI / 8 <= direction < 3 * PI / 8
or 9 * PI / 8 <= direction < 11 * PI / 8
):
sw = sobel_grad[row + 1, col - 1]
ne = sobel_grad[row - 1, col + 1]
if sobel_grad[row, col] >= sw and sobel_grad[row, col] >= ne:
destination[row, col] = sobel_grad[row, col]
elif (
3 * PI / 8 <= direction < 5 * PI / 8
or 11 * PI / 8 <= direction < 13 * PI / 8
):
n = sobel_grad[row - 1, col]
s = sobel_grad[row + 1, col]
if sobel_grad[row, col] >= n and sobel_grad[row, col] >= s:
destination[row, col] = sobel_grad[row, col]
elif (
5 * PI / 8 <= direction < 7 * PI / 8
or 13 * PI / 8 <= direction < 15 * PI / 8
):
nw = sobel_grad[row - 1, col - 1]
se = sobel_grad[row + 1, col + 1]
if sobel_grad[row, col] >= nw and sobel_grad[row, col] >= se:
destination[row, col] = sobel_grad[row, col]
return destination
def detect_high_low_threshold(
image_shape, destination, threshold_low, threshold_high, weak, strong
):
"""
High-Low threshold detection. If an edge pixel's gradient value is higher
than the high threshold value, it is marked as a strong edge pixel. If an
edge pixel's gradient value is smaller than the high threshold value and
larger than the low threshold value, it is marked as a weak edge pixel. If
an edge pixel's value is smaller than the low threshold value, it will be
suppressed.
"""
for row in range(1, image_shape[0] - 1):
for col in range(1, image_shape[1] - 1):
if destination[row, col] >= threshold_high:
destination[row, col] = strong
elif destination[row, col] <= threshold_low:
destination[row, col] = 0
else:
destination[row, col] = weak
def track_edge(image_shape, destination, weak, strong):
"""
Edge tracking. Usually a weak edge pixel caused from true edges will be connected
to a strong edge pixel while noise responses are unconnected. As long as there is
one strong edge pixel that is involved in its 8-connected neighborhood, that weak
edge point can be identified as one that should be preserved.
"""
for row in range(1, image_shape[0]):
for col in range(1, image_shape[1]):
if destination[row, col] == weak:
if 255 in (
destination[row, col + 1],
destination[row, col - 1],
destination[row - 1, col],
destination[row + 1, col],
destination[row - 1, col - 1],
destination[row + 1, col - 1],
destination[row - 1, col + 1],
destination[row + 1, col + 1],
):
destination[row, col] = strong
else:
destination[row, col] = 0
def canny(image, threshold_low=15, threshold_high=30, weak=128, strong=255):
# gaussian_filter
gaussian_out = img_convolve(image, gen_gaussian_kernel(9, sigma=1.4))
# get the gradient and degree by sobel_filter
sobel_grad, sobel_theta = sobel_filter(gaussian_out)
gradient_direction = PI + np.rad2deg(sobel_theta)
destination = suppress_non_maximum(image.shape, gradient_direction, sobel_grad)
detect_high_low_threshold(
image.shape, destination, threshold_low, threshold_high, weak, strong
)
track_edge(image.shape, destination, weak, strong)
return destination
if __name__ == "__main__":
# read original image in gray mode
lena = cv2.imread(r"../image_data/lena.jpg", 0)
# canny edge detection
canny_destination = canny(lena)
cv2.imshow("canny", canny_destination)
cv2.waitKey(0)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/edge_detection/__init__.py | digital_image_processing/edge_detection/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/dithering/__init__.py | digital_image_processing/dithering/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/dithering/burkes.py | digital_image_processing/dithering/burkes.py | """
Implementation Burke's algorithm (dithering)
"""
import numpy as np
from cv2 import destroyAllWindows, imread, imshow, waitKey
class Burkes:
"""
Burke's algorithm is using for converting grayscale image to black and white version
Source: Source: https://en.wikipedia.org/wiki/Dither
Note:
* Best results are given with threshold= ~1/2 * max greyscale value.
* This implementation get RGB image and converts it to greyscale in runtime.
"""
def __init__(self, input_img, threshold: int):
self.min_threshold = 0
# max greyscale value for #FFFFFF
self.max_threshold = int(self.get_greyscale(255, 255, 255))
if not self.min_threshold < threshold < self.max_threshold:
msg = f"Factor value should be from 0 to {self.max_threshold}"
raise ValueError(msg)
self.input_img = input_img
self.threshold = threshold
self.width, self.height = self.input_img.shape[1], self.input_img.shape[0]
# error table size (+4 columns and +1 row) greater than input image because of
# lack of if statements
self.error_table = [
[0 for _ in range(self.height + 4)] for __ in range(self.width + 1)
]
self.output_img = np.ones((self.width, self.height, 3), np.uint8) * 255
@classmethod
def get_greyscale(cls, blue: int, green: int, red: int) -> float:
"""
>>> Burkes.get_greyscale(3, 4, 5)
4.185
>>> Burkes.get_greyscale(0, 0, 0)
0.0
>>> Burkes.get_greyscale(255, 255, 255)
255.0
"""
"""
Formula from https://en.wikipedia.org/wiki/HSL_and_HSV
cf Lightness section, and Fig 13c.
We use the first of four possible.
"""
return 0.114 * blue + 0.587 * green + 0.299 * red
def process(self) -> None:
for y in range(self.height):
for x in range(self.width):
greyscale = int(self.get_greyscale(*self.input_img[y][x]))
if self.threshold > greyscale + self.error_table[y][x]:
self.output_img[y][x] = (0, 0, 0)
current_error = greyscale + self.error_table[y][x]
else:
self.output_img[y][x] = (255, 255, 255)
current_error = greyscale + self.error_table[y][x] - 255
"""
Burkes error propagation (`*` is current pixel):
* 8/32 4/32
2/32 4/32 8/32 4/32 2/32
"""
self.error_table[y][x + 1] += int(8 / 32 * current_error)
self.error_table[y][x + 2] += int(4 / 32 * current_error)
self.error_table[y + 1][x] += int(8 / 32 * current_error)
self.error_table[y + 1][x + 1] += int(4 / 32 * current_error)
self.error_table[y + 1][x + 2] += int(2 / 32 * current_error)
self.error_table[y + 1][x - 1] += int(4 / 32 * current_error)
self.error_table[y + 1][x - 2] += int(2 / 32 * current_error)
if __name__ == "__main__":
# create Burke's instances with original images in greyscale
burkes_instances = [
Burkes(imread("image_data/lena.jpg", 1), threshold)
for threshold in (1, 126, 130, 140)
]
for burkes in burkes_instances:
burkes.process()
for burkes in burkes_instances:
imshow(
f"Original image with dithering threshold: {burkes.threshold}",
burkes.output_img,
)
waitKey(0)
destroyAllWindows()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/rotation/rotation.py | digital_image_processing/rotation/rotation.py | from pathlib import Path
import cv2
import numpy as np
from matplotlib import pyplot as plt
def get_rotation(
img: np.ndarray, pt1: np.ndarray, pt2: np.ndarray, rows: int, cols: int
) -> np.ndarray:
"""
Get image rotation
:param img: np.ndarray
:param pt1: 3x2 list
:param pt2: 3x2 list
:param rows: columns image shape
:param cols: rows image shape
:return: np.ndarray
"""
matrix = cv2.getAffineTransform(pt1, pt2)
return cv2.warpAffine(img, matrix, (rows, cols))
if __name__ == "__main__":
# read original image
image = cv2.imread(
str(Path(__file__).resolve().parent.parent / "image_data" / "lena.jpg")
)
# turn image in gray scale value
gray_img = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# get image shape
img_rows, img_cols = gray_img.shape
# set different points to rotate image
pts1 = np.array([[50, 50], [200, 50], [50, 200]], np.float32)
pts2 = np.array([[10, 100], [200, 50], [100, 250]], np.float32)
pts3 = np.array([[50, 50], [150, 50], [120, 200]], np.float32)
pts4 = np.array([[10, 100], [80, 50], [180, 250]], np.float32)
# add all rotated images in a list
images = [
gray_img,
get_rotation(gray_img, pts1, pts2, img_rows, img_cols),
get_rotation(gray_img, pts2, pts3, img_rows, img_cols),
get_rotation(gray_img, pts2, pts4, img_rows, img_cols),
]
# plot different image rotations
fig = plt.figure(1)
titles = ["Original", "Rotation 1", "Rotation 2", "Rotation 3"]
for i, image in enumerate(images):
plt.subplot(2, 2, i + 1), plt.imshow(image, "gray")
plt.title(titles[i])
plt.axis("off")
plt.subplots_adjust(left=0.0, bottom=0.05, right=1.0, top=0.95)
plt.show()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/digital_image_processing/rotation/__init__.py | digital_image_processing/rotation/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/genetic_algorithm/basic_string.py | genetic_algorithm/basic_string.py | """
Simple multithreaded algorithm to show how the 4 phases of a genetic algorithm works
(Evaluation, Selection, Crossover and Mutation)
https://en.wikipedia.org/wiki/Genetic_algorithm
Author: D4rkia
"""
from __future__ import annotations
import random
# Maximum size of the population. Bigger could be faster but is more memory expensive.
N_POPULATION = 200
# Number of elements selected in every generation of evolution. The selection takes
# place from best to worst of that generation and must be smaller than N_POPULATION.
N_SELECTED = 50
# Probability that an element of a generation can mutate, changing one of its genes.
# This will guarantee that all genes will be used during evolution.
MUTATION_PROBABILITY = 0.4
# Just a seed to improve randomness required by the algorithm.
random.seed(random.randint(0, 1000))
def evaluate(item: str, main_target: str) -> tuple[str, float]:
"""
Evaluate how similar the item is with the target by just
counting each char in the right position
>>> evaluate("Helxo Worlx", "Hello World")
('Helxo Worlx', 9.0)
"""
score = len([g for position, g in enumerate(item) if g == main_target[position]])
return (item, float(score))
def crossover(parent_1: str, parent_2: str) -> tuple[str, str]:
"""
Slice and combine two strings at a random point.
>>> random.seed(42)
>>> crossover("123456", "abcdef")
('12345f', 'abcde6')
"""
random_slice = random.randint(0, len(parent_1) - 1)
child_1 = parent_1[:random_slice] + parent_2[random_slice:]
child_2 = parent_2[:random_slice] + parent_1[random_slice:]
return (child_1, child_2)
def mutate(child: str, genes: list[str]) -> str:
"""
Mutate a random gene of a child with another one from the list.
>>> random.seed(123)
>>> mutate("123456", list("ABCDEF"))
'12345A'
"""
child_list = list(child)
if random.uniform(0, 1) < MUTATION_PROBABILITY:
child_list[random.randint(0, len(child)) - 1] = random.choice(genes)
return "".join(child_list)
# Select, crossover and mutate a new population.
def select(
parent_1: tuple[str, float],
population_score: list[tuple[str, float]],
genes: list[str],
) -> list[str]:
"""
Select the second parent and generate new population
>>> random.seed(42)
>>> parent_1 = ("123456", 8.0)
>>> population_score = [("abcdef", 4.0), ("ghijkl", 5.0), ("mnopqr", 7.0)]
>>> genes = list("ABCDEF")
>>> child_n = int(min(parent_1[1] + 1, 10))
>>> population = []
>>> for _ in range(child_n):
... parent_2 = population_score[random.randrange(len(population_score))][0]
... child_1, child_2 = crossover(parent_1[0], parent_2)
... population.extend((mutate(child_1, genes), mutate(child_2, genes)))
>>> len(population) == (int(parent_1[1]) + 1) * 2
True
"""
pop = []
# Generate more children proportionally to the fitness score.
child_n = int(parent_1[1] * 100) + 1
child_n = 10 if child_n >= 10 else child_n
for _ in range(child_n):
parent_2 = population_score[random.randint(0, N_SELECTED)][0]
child_1, child_2 = crossover(parent_1[0], parent_2)
# Append new string to the population list.
pop.append(mutate(child_1, genes))
pop.append(mutate(child_2, genes))
return pop
def basic(target: str, genes: list[str], debug: bool = True) -> tuple[int, int, str]:
"""
Verify that the target contains no genes besides the ones inside genes variable.
>>> from string import ascii_lowercase
>>> basic("doctest", ascii_lowercase, debug=False)[2]
'doctest'
>>> genes = list(ascii_lowercase)
>>> genes.remove("e")
>>> basic("test", genes)
Traceback (most recent call last):
...
ValueError: ['e'] is not in genes list, evolution cannot converge
>>> genes.remove("s")
>>> basic("test", genes)
Traceback (most recent call last):
...
ValueError: ['e', 's'] is not in genes list, evolution cannot converge
>>> genes.remove("t")
>>> basic("test", genes)
Traceback (most recent call last):
...
ValueError: ['e', 's', 't'] is not in genes list, evolution cannot converge
"""
# Verify if N_POPULATION is bigger than N_SELECTED
if N_POPULATION < N_SELECTED:
msg = f"{N_POPULATION} must be bigger than {N_SELECTED}"
raise ValueError(msg)
# Verify that the target contains no genes besides the ones inside genes variable.
not_in_genes_list = sorted({c for c in target if c not in genes})
if not_in_genes_list:
msg = f"{not_in_genes_list} is not in genes list, evolution cannot converge"
raise ValueError(msg)
# Generate random starting population.
population = []
for _ in range(N_POPULATION):
population.append("".join([random.choice(genes) for i in range(len(target))]))
# Just some logs to know what the algorithms is doing.
generation, total_population = 0, 0
# This loop will end when we find a perfect match for our target.
while True:
generation += 1
total_population += len(population)
# Random population created. Now it's time to evaluate.
# (Option 1) Adding a bit of concurrency can make everything faster,
#
# import concurrent.futures
# population_score: list[tuple[str, float]] = []
# with concurrent.futures.ThreadPoolExecutor(
# max_workers=NUM_WORKERS) as executor:
# futures = {executor.submit(evaluate, item, target) for item in population}
# concurrent.futures.wait(futures)
# population_score = [item.result() for item in futures]
#
# but with a simple algorithm like this, it will probably be slower.
# (Option 2) We just need to call evaluate for every item inside the population.
population_score = [evaluate(item, target) for item in population]
# Check if there is a matching evolution.
population_score = sorted(population_score, key=lambda x: x[1], reverse=True)
if population_score[0][0] == target:
return (generation, total_population, population_score[0][0])
# Print the best result every 10 generation.
# Just to know that the algorithm is working.
if debug and generation % 10 == 0:
print(
f"\nGeneration: {generation}"
f"\nTotal Population:{total_population}"
f"\nBest score: {population_score[0][1]}"
f"\nBest string: {population_score[0][0]}"
)
# Flush the old population, keeping some of the best evolutions.
# Keeping this avoid regression of evolution.
population_best = population[: int(N_POPULATION / 3)]
population.clear()
population.extend(population_best)
# Normalize population score to be between 0 and 1.
population_score = [
(item, score / len(target)) for item, score in population_score
]
# This is selection
for i in range(N_SELECTED):
population.extend(select(population_score[int(i)], population_score, genes))
# Check if the population has already reached the maximum value and if so,
# break the cycle. If this check is disabled, the algorithm will take
# forever to compute large strings, but will also calculate small strings in
# a far fewer generations.
if len(population) > N_POPULATION:
break
if __name__ == "__main__":
target_str = (
"This is a genetic algorithm to evaluate, combine, evolve, and mutate a string!"
)
genes_list = list(
" ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklm"
"nopqrstuvwxyz.,;!?+-*#@^'èéòà€ù=)(&%$£/\\"
)
generation, population, target = basic(target_str, genes_list)
print(
f"\nGeneration: {generation}\nTotal Population: {population}\nTarget: {target}"
)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/genetic_algorithm/__init__.py | genetic_algorithm/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/quantum/q_fourier_transform.py | quantum/q_fourier_transform.py | """
Build the quantum fourier transform (qft) for a desire
number of quantum bits using Qiskit framework. This
experiment run in IBM Q simulator with 10000 shots.
This circuit can be use as a building block to design
the Shor's algorithm in quantum computing. As well as,
quantum phase estimation among others.
.
References:
https://en.wikipedia.org/wiki/Quantum_Fourier_transform
https://qiskit.org/textbook/ch-algorithms/quantum-fourier-transform.html
"""
import math
import numpy as np
import qiskit
from qiskit import Aer, ClassicalRegister, QuantumCircuit, QuantumRegister, execute
def quantum_fourier_transform(number_of_qubits: int = 3) -> qiskit.result.counts.Counts:
"""
# >>> quantum_fourier_transform(2)
# {'00': 2500, '01': 2500, '11': 2500, '10': 2500}
# quantum circuit for number_of_qubits = 3:
┌───┐
qr_0: ──────■──────────────────────■───────┤ H ├─X─
│ ┌───┐ │P(π/2) └───┘ │
qr_1: ──────┼────────■───────┤ H ├─■─────────────┼─
┌───┐ │P(π/4) │P(π/2) └───┘ │
qr_2: ┤ H ├─■────────■───────────────────────────X─
└───┘
cr: 3/═════════════════════════════════════════════
Args:
n : number of qubits
Returns:
qiskit.result.counts.Counts: distribute counts.
>>> quantum_fourier_transform(2)
{'00': 2500, '01': 2500, '10': 2500, '11': 2500}
>>> quantum_fourier_transform(-1)
Traceback (most recent call last):
...
ValueError: number of qubits must be > 0.
>>> quantum_fourier_transform('a')
Traceback (most recent call last):
...
TypeError: number of qubits must be a integer.
>>> quantum_fourier_transform(100)
Traceback (most recent call last):
...
ValueError: number of qubits too large to simulate(>10).
>>> quantum_fourier_transform(0.5)
Traceback (most recent call last):
...
ValueError: number of qubits must be exact integer.
"""
if isinstance(number_of_qubits, str):
raise TypeError("number of qubits must be a integer.")
if number_of_qubits <= 0:
raise ValueError("number of qubits must be > 0.")
if math.floor(number_of_qubits) != number_of_qubits:
raise ValueError("number of qubits must be exact integer.")
if number_of_qubits > 10:
raise ValueError("number of qubits too large to simulate(>10).")
qr = QuantumRegister(number_of_qubits, "qr")
cr = ClassicalRegister(number_of_qubits, "cr")
quantum_circuit = QuantumCircuit(qr, cr)
counter = number_of_qubits
for i in range(counter):
quantum_circuit.h(number_of_qubits - i - 1)
counter -= 1
for j in range(counter):
quantum_circuit.cp(np.pi / 2 ** (counter - j), j, counter)
for k in range(number_of_qubits // 2):
quantum_circuit.swap(k, number_of_qubits - k - 1)
# measure all the qubits
quantum_circuit.measure(qr, cr)
# simulate with 10000 shots
backend = Aer.get_backend("qasm_simulator")
job = execute(quantum_circuit, backend, shots=10000)
return job.result().get_counts(quantum_circuit)
if __name__ == "__main__":
print(
f"Total count for quantum fourier transform state is: \
{quantum_fourier_transform(3)}"
)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/quantum/__init__.py | quantum/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/intro_sort.py | sorts/intro_sort.py | """
Introspective Sort is a hybrid sort (Quick Sort + Heap Sort + Insertion Sort)
if the size of the list is under 16, use insertion sort
https://en.wikipedia.org/wiki/Introsort
"""
import math
def insertion_sort(array: list, start: int = 0, end: int = 0) -> list:
"""
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> insertion_sort(array, 0, len(array))
[1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79]
>>> array = [21, 15, 11, 45, -2, -11, 46]
>>> insertion_sort(array, 0, len(array))
[-11, -2, 11, 15, 21, 45, 46]
>>> array = [-2, 0, 89, 11, 48, 79, 12]
>>> insertion_sort(array, 0, len(array))
[-2, 0, 11, 12, 48, 79, 89]
>>> array = ['a', 'z', 'd', 'p', 'v', 'l', 'o', 'o']
>>> insertion_sort(array, 0, len(array))
['a', 'd', 'l', 'o', 'o', 'p', 'v', 'z']
>>> array = [73.568, 73.56, -45.03, 1.7, 0, 89.45]
>>> insertion_sort(array, 0, len(array))
[-45.03, 0, 1.7, 73.56, 73.568, 89.45]
"""
end = end or len(array)
for i in range(start, end):
temp_index = i
temp_index_value = array[i]
while temp_index != start and temp_index_value < array[temp_index - 1]:
array[temp_index] = array[temp_index - 1]
temp_index -= 1
array[temp_index] = temp_index_value
return array
def heapify(array: list, index: int, heap_size: int) -> None: # Max Heap
"""
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> heapify(array, len(array) // 2, len(array))
"""
largest = index
left_index = 2 * index + 1 # Left Node
right_index = 2 * index + 2 # Right Node
if left_index < heap_size and array[largest] < array[left_index]:
largest = left_index
if right_index < heap_size and array[largest] < array[right_index]:
largest = right_index
if largest != index:
array[index], array[largest] = array[largest], array[index]
heapify(array, largest, heap_size)
def heap_sort(array: list) -> list:
"""
>>> heap_sort([4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12])
[1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79]
>>> heap_sort([-2, -11, 0, 0, 0, 87, 45, -69, 78, 12, 10, 103, 89, 52])
[-69, -11, -2, 0, 0, 0, 10, 12, 45, 52, 78, 87, 89, 103]
>>> heap_sort(['b', 'd', 'e', 'f', 'g', 'p', 'x', 'z', 'b', 's', 'e', 'u', 'v'])
['b', 'b', 'd', 'e', 'e', 'f', 'g', 'p', 's', 'u', 'v', 'x', 'z']
>>> heap_sort([6.2, -45.54, 8465.20, 758.56, -457.0, 0, 1, 2.879, 1.7, 11.7])
[-457.0, -45.54, 0, 1, 1.7, 2.879, 6.2, 11.7, 758.56, 8465.2]
"""
n = len(array)
for i in range(n // 2, -1, -1):
heapify(array, i, n)
for i in range(n - 1, 0, -1):
array[i], array[0] = array[0], array[i]
heapify(array, 0, i)
return array
def median_of_3(
array: list, first_index: int, middle_index: int, last_index: int
) -> int:
"""
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> median_of_3(array, 0, ((len(array) - 0) // 2) + 1, len(array) - 1)
12
>>> array = [13, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> median_of_3(array, 0, ((len(array) - 0) // 2) + 1, len(array) - 1)
13
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 15, 14, 27, 79, 23, 45, 14, 16]
>>> median_of_3(array, 0, ((len(array) - 0) // 2) + 1, len(array) - 1)
14
"""
if (array[first_index] > array[middle_index]) != (
array[first_index] > array[last_index]
):
return array[first_index]
elif (array[middle_index] > array[first_index]) != (
array[middle_index] > array[last_index]
):
return array[middle_index]
else:
return array[last_index]
def partition(array: list, low: int, high: int, pivot: int) -> int:
"""
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> partition(array, 0, len(array), 12)
8
>>> array = [21, 15, 11, 45, -2, -11, 46]
>>> partition(array, 0, len(array), 15)
3
>>> array = ['a', 'z', 'd', 'p', 'v', 'l', 'o', 'o']
>>> partition(array, 0, len(array), 'p')
5
>>> array = [6.2, -45.54, 8465.20, 758.56, -457.0, 0, 1, 2.879, 1.7, 11.7]
>>> partition(array, 0, len(array), 2.879)
6
"""
i = low
j = high
while True:
while array[i] < pivot:
i += 1
j -= 1
while pivot < array[j]:
j -= 1
if i >= j:
return i
array[i], array[j] = array[j], array[i]
i += 1
def sort(array: list) -> list:
"""
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> sort([4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12])
[1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79]
>>> sort([-1, -5, -3, -13, -44])
[-44, -13, -5, -3, -1]
>>> sort([])
[]
>>> sort([5])
[5]
>>> sort([-3, 0, -7, 6, 23, -34])
[-34, -7, -3, 0, 6, 23]
>>> sort([1.7, 1.0, 3.3, 2.1, 0.3 ])
[0.3, 1.0, 1.7, 2.1, 3.3]
>>> sort(['d', 'a', 'b', 'e', 'c'])
['a', 'b', 'c', 'd', 'e']
"""
if len(array) == 0:
return array
max_depth = 2 * math.ceil(math.log2(len(array)))
size_threshold = 16
return intro_sort(array, 0, len(array), size_threshold, max_depth)
def intro_sort(
array: list, start: int, end: int, size_threshold: int, max_depth: int
) -> list:
"""
>>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]
>>> max_depth = 2 * math.ceil(math.log2(len(array)))
>>> intro_sort(array, 0, len(array), 16, max_depth)
[1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79]
"""
while end - start > size_threshold:
if max_depth == 0:
return heap_sort(array)
max_depth -= 1
pivot = median_of_3(array, start, start + ((end - start) // 2) + 1, end - 1)
p = partition(array, start, end, pivot)
intro_sort(array, p, end, size_threshold, max_depth)
end = p
return insertion_sort(array, start, end)
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by a comma : ").strip()
unsorted = [float(item) for item in user_input.split(",")]
print(f"{sort(unsorted) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/strand_sort.py | sorts/strand_sort.py | import operator
def strand_sort(arr: list, reverse: bool = False, solution: list | None = None) -> list:
"""
Strand sort implementation
source: https://en.wikipedia.org/wiki/Strand_sort
:param arr: Unordered input list
:param reverse: Descent ordering flag
:param solution: Ordered items container
Examples:
>>> strand_sort([4, 2, 5, 3, 0, 1])
[0, 1, 2, 3, 4, 5]
>>> strand_sort([4, 2, 5, 3, 0, 1], reverse=True)
[5, 4, 3, 2, 1, 0]
"""
_operator = operator.lt if reverse else operator.gt
solution = solution or []
if not arr:
return solution
sublist = [arr.pop(0)]
for i, item in enumerate(arr):
if _operator(item, sublist[-1]):
sublist.append(item)
arr.pop(i)
# merging sublist into solution list
if not solution:
solution.extend(sublist)
else:
while sublist:
item = sublist.pop(0)
for i, xx in enumerate(solution):
if not _operator(item, xx):
solution.insert(i, item)
break
else:
solution.append(item)
strand_sort(arr, reverse, solution)
return solution
if __name__ == "__main__":
assert strand_sort([4, 3, 5, 1, 2]) == [1, 2, 3, 4, 5]
assert strand_sort([4, 3, 5, 1, 2], reverse=True) == [5, 4, 3, 2, 1]
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/wiggle_sort.py | sorts/wiggle_sort.py | """
Wiggle Sort.
Given an unsorted array nums, reorder it such
that nums[0] < nums[1] > nums[2] < nums[3]....
For example:
if input numbers = [3, 5, 2, 1, 6, 4]
one possible Wiggle Sorted answer is [3, 5, 1, 6, 2, 4].
"""
def wiggle_sort(nums: list) -> list:
"""
Python implementation of wiggle.
Example:
>>> wiggle_sort([0, 5, 3, 2, 2])
[0, 5, 2, 3, 2]
>>> wiggle_sort([])
[]
>>> wiggle_sort([-2, -5, -45])
[-45, -2, -5]
>>> wiggle_sort([-2.1, -5.68, -45.11])
[-45.11, -2.1, -5.68]
"""
for i, _ in enumerate(nums):
if (i % 2 == 1) == (nums[i - 1] > nums[i]):
nums[i - 1], nums[i] = nums[i], nums[i - 1]
return nums
if __name__ == "__main__":
print("Enter the array elements:")
array = list(map(int, input().split()))
print("The unsorted array is:")
print(array)
print("Array after Wiggle sort:")
print(wiggle_sort(array))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/odd_even_transposition_parallel.py | sorts/odd_even_transposition_parallel.py | """
This is an implementation of odd-even transposition sort.
It works by performing a series of parallel swaps between odd and even pairs of
variables in the list.
This implementation represents each variable in the list with a process and
each process communicates with its neighboring processes in the list to perform
comparisons.
They are synchronized with locks and message passing but other forms of
synchronization could be used.
"""
import multiprocessing as mp
# lock used to ensure that two processes do not access a pipe at the same time
# NOTE This breaks testing on build runner. May work better locally
# process_lock = mp.Lock()
"""
The function run by the processes that sorts the list
position = the position in the list the process represents, used to know which
neighbor we pass our value to
value = the initial value at list[position]
LSend, RSend = the pipes we use to send to our left and right neighbors
LRcv, RRcv = the pipes we use to receive from our left and right neighbors
resultPipe = the pipe used to send results back to main
"""
def oe_process(
position,
value,
l_send,
r_send,
lr_cv,
rr_cv,
result_pipe,
multiprocessing_context,
):
process_lock = multiprocessing_context.Lock()
# we perform n swaps since after n swaps we know we are sorted
# we *could* stop early if we are sorted already, but it takes as long to
# find out we are sorted as it does to sort the list with this algorithm
for i in range(10):
if (i + position) % 2 == 0 and r_send is not None:
# send your value to your right neighbor
with process_lock:
r_send[1].send(value)
# receive your right neighbor's value
with process_lock:
temp = rr_cv[0].recv()
# take the lower value since you are on the left
value = min(value, temp)
elif (i + position) % 2 != 0 and l_send is not None:
# send your value to your left neighbor
with process_lock:
l_send[1].send(value)
# receive your left neighbor's value
with process_lock:
temp = lr_cv[0].recv()
# take the higher value since you are on the right
value = max(value, temp)
# after all swaps are performed, send the values back to main
result_pipe[1].send(value)
"""
the function which creates the processes that perform the parallel swaps
arr = the list to be sorted
"""
def odd_even_transposition(arr):
"""
>>> odd_even_transposition(list(range(10)[::-1])) == sorted(list(range(10)[::-1]))
True
>>> odd_even_transposition(["a", "x", "c"]) == sorted(["x", "a", "c"])
True
>>> odd_even_transposition([1.9, 42.0, 2.8]) == sorted([1.9, 42.0, 2.8])
True
>>> odd_even_transposition([False, True, False]) == sorted([False, False, True])
True
>>> odd_even_transposition([1, 32.0, 9]) == sorted([False, False, True])
False
>>> odd_even_transposition([1, 32.0, 9]) == sorted([1.0, 32, 9.0])
True
>>> unsorted_list = [-442, -98, -554, 266, -491, 985, -53, -529, 82, -429]
>>> odd_even_transposition(unsorted_list) == sorted(unsorted_list)
True
>>> unsorted_list = [-442, -98, -554, 266, -491, 985, -53, -529, 82, -429]
>>> odd_even_transposition(unsorted_list) == sorted(unsorted_list + [1])
False
"""
# spawn method is considered safer than fork
multiprocessing_context = mp.get_context("spawn")
process_array_ = []
result_pipe = []
# initialize the list of pipes where the values will be retrieved
for _ in arr:
result_pipe.append(multiprocessing_context.Pipe())
# creates the processes
# the first and last process only have one neighbor so they are made outside
# of the loop
temp_rs = multiprocessing_context.Pipe()
temp_rr = multiprocessing_context.Pipe()
process_array_.append(
multiprocessing_context.Process(
target=oe_process,
args=(
0,
arr[0],
None,
temp_rs,
None,
temp_rr,
result_pipe[0],
multiprocessing_context,
),
)
)
temp_lr = temp_rs
temp_ls = temp_rr
for i in range(1, len(arr) - 1):
temp_rs = multiprocessing_context.Pipe()
temp_rr = multiprocessing_context.Pipe()
process_array_.append(
multiprocessing_context.Process(
target=oe_process,
args=(
i,
arr[i],
temp_ls,
temp_rs,
temp_lr,
temp_rr,
result_pipe[i],
multiprocessing_context,
),
)
)
temp_lr = temp_rs
temp_ls = temp_rr
process_array_.append(
multiprocessing_context.Process(
target=oe_process,
args=(
len(arr) - 1,
arr[len(arr) - 1],
temp_ls,
None,
temp_lr,
None,
result_pipe[len(arr) - 1],
multiprocessing_context,
),
)
)
# start the processes
for p in process_array_:
p.start()
# wait for the processes to end and write their values to the list
for p in range(len(result_pipe)):
arr[p] = result_pipe[p][0].recv()
process_array_[p].join()
return arr
# creates a reverse sorted list and sorts it
def main():
arr = list(range(10, 0, -1))
print("Initial List")
print(*arr)
arr = odd_even_transposition(arr)
print("Sorted List\n")
print(*arr)
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/exchange_sort.py | sorts/exchange_sort.py | def exchange_sort(numbers: list[int]) -> list[int]:
"""
Uses exchange sort to sort a list of numbers.
Source: https://en.wikipedia.org/wiki/Sorting_algorithm#Exchange_sort
>>> exchange_sort([5, 4, 3, 2, 1])
[1, 2, 3, 4, 5]
>>> exchange_sort([-1, -2, -3])
[-3, -2, -1]
>>> exchange_sort([1, 2, 3, 4, 5])
[1, 2, 3, 4, 5]
>>> exchange_sort([0, 10, -2, 5, 3])
[-2, 0, 3, 5, 10]
>>> exchange_sort([])
[]
"""
numbers_length = len(numbers)
for i in range(numbers_length):
for j in range(i + 1, numbers_length):
if numbers[j] < numbers[i]:
numbers[i], numbers[j] = numbers[j], numbers[i]
return numbers
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(exchange_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/iterative_merge_sort.py | sorts/iterative_merge_sort.py | """
Implementation of iterative merge sort in Python
Author: Aman Gupta
For doctests run following command:
python3 -m doctest -v iterative_merge_sort.py
For manual testing run:
python3 iterative_merge_sort.py
"""
from __future__ import annotations
def merge(input_list: list, low: int, mid: int, high: int) -> list:
"""
sorting left-half and right-half individually
then merging them into result
"""
result = []
left, right = input_list[low:mid], input_list[mid : high + 1]
while left and right:
result.append((left if left[0] <= right[0] else right).pop(0))
input_list[low : high + 1] = result + left + right
return input_list
# iteration over the unsorted list
def iter_merge_sort(input_list: list) -> list:
"""
Return a sorted copy of the input list
>>> iter_merge_sort([5, 9, 8, 7, 1, 2, 7])
[1, 2, 5, 7, 7, 8, 9]
>>> iter_merge_sort([1])
[1]
>>> iter_merge_sort([2, 1])
[1, 2]
>>> iter_merge_sort([2, 1, 3])
[1, 2, 3]
>>> iter_merge_sort([4, 3, 2, 1])
[1, 2, 3, 4]
>>> iter_merge_sort([5, 4, 3, 2, 1])
[1, 2, 3, 4, 5]
>>> iter_merge_sort(['c', 'b', 'a'])
['a', 'b', 'c']
>>> iter_merge_sort([0.3, 0.2, 0.1])
[0.1, 0.2, 0.3]
>>> iter_merge_sort(['dep', 'dang', 'trai'])
['dang', 'dep', 'trai']
>>> iter_merge_sort([6])
[6]
>>> iter_merge_sort([])
[]
>>> iter_merge_sort([-2, -9, -1, -4])
[-9, -4, -2, -1]
>>> iter_merge_sort([1.1, 1, 0.0, -1, -1.1])
[-1.1, -1, 0.0, 1, 1.1]
>>> iter_merge_sort(['c', 'b', 'a'])
['a', 'b', 'c']
>>> iter_merge_sort('cba')
['a', 'b', 'c']
"""
if len(input_list) <= 1:
return input_list
input_list = list(input_list)
# iteration for two-way merging
p = 2
while p <= len(input_list):
# getting low, high and middle value for merge-sort of single list
for i in range(0, len(input_list), p):
low = i
high = i + p - 1
mid = (low + high + 1) // 2
input_list = merge(input_list, low, mid, high)
# final merge of last two parts
if p * 2 >= len(input_list):
mid = i
input_list = merge(input_list, 0, mid, len(input_list) - 1)
break
p *= 2
return input_list
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
if user_input == "":
unsorted = []
else:
unsorted = [int(item.strip()) for item in user_input.split(",")]
print(iter_merge_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/double_sort.py | sorts/double_sort.py | from typing import Any
def double_sort(collection: list[Any]) -> list[Any]:
"""This sorting algorithm sorts an array using the principle of bubble sort,
but does it both from left to right and right to left.
Hence, it's called "Double sort"
:param collection: mutable ordered sequence of elements
:return: the same collection in ascending order
Examples:
>>> double_sort([-1 ,-2 ,-3 ,-4 ,-5 ,-6 ,-7])
[-7, -6, -5, -4, -3, -2, -1]
>>> double_sort([])
[]
>>> double_sort([-1 ,-2 ,-3 ,-4 ,-5 ,-6])
[-6, -5, -4, -3, -2, -1]
>>> double_sort([-3, 10, 16, -42, 29]) == sorted([-3, 10, 16, -42, 29])
True
"""
no_of_elements = len(collection)
for _ in range(
int(((no_of_elements - 1) / 2) + 1)
): # we don't need to traverse to end of list as
for j in range(no_of_elements - 1):
# apply the bubble sort algorithm from left to right (or forwards)
if collection[j + 1] < collection[j]:
collection[j], collection[j + 1] = collection[j + 1], collection[j]
# apply the bubble sort algorithm from right to left (or backwards)
if collection[no_of_elements - 1 - j] < collection[no_of_elements - 2 - j]:
(
collection[no_of_elements - 1 - j],
collection[no_of_elements - 2 - j],
) = (
collection[no_of_elements - 2 - j],
collection[no_of_elements - 1 - j],
)
return collection
if __name__ == "__main__":
# allow the user to input the elements of the list on one line
unsorted = [int(x) for x in input("Enter the list to be sorted: ").split() if x]
print("the sorted list is")
print(f"{double_sort(unsorted) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/binary_insertion_sort.py | sorts/binary_insertion_sort.py | """
This is a pure Python implementation of the binary insertion sort algorithm
For doctests run following command:
python -m doctest -v binary_insertion_sort.py
or
python3 -m doctest -v binary_insertion_sort.py
For manual testing run:
python binary_insertion_sort.py
"""
def binary_insertion_sort(collection: list) -> list:
"""
Sorts a list using the binary insertion sort algorithm.
:param collection: A mutable ordered collection with comparable items.
:return: The same collection ordered in ascending order.
Examples:
>>> binary_insertion_sort([0, 4, 1234, 4, 1])
[0, 1, 4, 4, 1234]
>>> binary_insertion_sort([]) == sorted([])
True
>>> binary_insertion_sort([-1, -2, -3]) == sorted([-1, -2, -3])
True
>>> lst = ['d', 'a', 'b', 'e', 'c']
>>> binary_insertion_sort(lst) == sorted(lst)
True
>>> import random
>>> collection = random.sample(range(-50, 50), 100)
>>> binary_insertion_sort(collection) == sorted(collection)
True
>>> import string
>>> collection = random.choices(string.ascii_letters + string.digits, k=100)
>>> binary_insertion_sort(collection) == sorted(collection)
True
"""
n = len(collection)
for i in range(1, n):
value_to_insert = collection[i]
low = 0
high = i - 1
while low <= high:
mid = (low + high) // 2
if value_to_insert < collection[mid]:
high = mid - 1
else:
low = mid + 1
for j in range(i, low, -1):
collection[j] = collection[j - 1]
collection[low] = value_to_insert
return collection
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
try:
unsorted = [int(item) for item in user_input.split(",")]
except ValueError:
print("Invalid input. Please enter valid integers separated by commas.")
raise
print(f"{binary_insertion_sort(unsorted) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/unknown_sort.py | sorts/unknown_sort.py | """
Python implementation of a sort algorithm.
Best Case Scenario : O(n)
Worst Case Scenario : O(n^2) because native Python functions:min, max and remove are
already O(n)
"""
def merge_sort(collection):
"""Pure implementation of the fastest merge sort algorithm in Python
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: a collection ordered by ascending
Examples:
>>> merge_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> merge_sort([])
[]
>>> merge_sort([-2, -5, -45])
[-45, -5, -2]
"""
start, end = [], []
while len(collection) > 1:
min_one, max_one = min(collection), max(collection)
start.append(min_one)
end.append(max_one)
collection.remove(min_one)
collection.remove(max_one)
end.reverse()
return start + collection + end
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(*merge_sort(unsorted), sep=",")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/pigeon_sort.py | sorts/pigeon_sort.py | """
This is an implementation of Pigeon Hole Sort.
For doctests run following command:
python3 -m doctest -v pigeon_sort.py
or
python -m doctest -v pigeon_sort.py
For manual testing run:
python pigeon_sort.py
"""
from __future__ import annotations
def pigeon_sort(array: list[int]) -> list[int]:
"""
Implementation of pigeon hole sort algorithm
:param array: Collection of comparable items
:return: Collection sorted in ascending order
>>> pigeon_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> pigeon_sort([])
[]
>>> pigeon_sort([-2, -5, -45])
[-45, -5, -2]
"""
if len(array) == 0:
return array
_min, _max = min(array), max(array)
# Compute the variables
holes_range = _max - _min + 1
holes, holes_repeat = [0] * holes_range, [0] * holes_range
# Make the sorting.
for i in array:
index = i - _min
holes[index] = i
holes_repeat[index] += 1
# Makes the array back by replacing the numbers.
index = 0
for i in range(holes_range):
while holes_repeat[i] > 0:
array[index] = holes[i]
index += 1
holes_repeat[i] -= 1
# Returns the sorted array.
return array
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by comma:\n")
unsorted = [int(x) for x in user_input.split(",")]
print(pigeon_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/bead_sort.py | sorts/bead_sort.py | """
Bead sort only works for sequences of non-negative integers.
https://en.wikipedia.org/wiki/Bead_sort
"""
def bead_sort(sequence: list) -> list:
"""
>>> bead_sort([6, 11, 12, 4, 1, 5])
[1, 4, 5, 6, 11, 12]
>>> bead_sort([9, 8, 7, 6, 5, 4 ,3, 2, 1])
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> bead_sort([5, 0, 4, 3])
[0, 3, 4, 5]
>>> bead_sort([8, 2, 1])
[1, 2, 8]
>>> bead_sort([1, .9, 0.0, 0, -1, -.9])
Traceback (most recent call last):
...
TypeError: Sequence must be list of non-negative integers
>>> bead_sort("Hello world")
Traceback (most recent call last):
...
TypeError: Sequence must be list of non-negative integers
"""
if any(not isinstance(x, int) or x < 0 for x in sequence):
raise TypeError("Sequence must be list of non-negative integers")
for _ in range(len(sequence)):
for i, (rod_upper, rod_lower) in enumerate(zip(sequence, sequence[1:])): # noqa: RUF007
if rod_upper > rod_lower:
sequence[i] -= rod_upper - rod_lower
sequence[i + 1] += rod_upper - rod_lower
return sequence
if __name__ == "__main__":
assert bead_sort([5, 4, 3, 2, 1]) == [1, 2, 3, 4, 5]
assert bead_sort([7, 9, 4, 3, 5]) == [3, 4, 5, 7, 9]
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/counting_sort.py | sorts/counting_sort.py | """
This is pure Python implementation of counting sort algorithm
For doctests run following command:
python -m doctest -v counting_sort.py
or
python3 -m doctest -v counting_sort.py
For manual testing run:
python counting_sort.py
"""
def counting_sort(collection):
"""Pure implementation of counting sort algorithm in Python
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> counting_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> counting_sort([])
[]
>>> counting_sort([-2, -5, -45])
[-45, -5, -2]
"""
# if the collection is empty, returns empty
if collection == []:
return []
# get some information about the collection
coll_len = len(collection)
coll_max = max(collection)
coll_min = min(collection)
# create the counting array
counting_arr_length = coll_max + 1 - coll_min
counting_arr = [0] * counting_arr_length
# count how much a number appears in the collection
for number in collection:
counting_arr[number - coll_min] += 1
# sum each position with it's predecessors. now, counting_arr[i] tells
# us how many elements <= i has in the collection
for i in range(1, counting_arr_length):
counting_arr[i] = counting_arr[i] + counting_arr[i - 1]
# create the output collection
ordered = [0] * coll_len
# place the elements in the output, respecting the original order (stable
# sort) from end to begin, updating counting_arr
for i in reversed(range(coll_len)):
ordered[counting_arr[collection[i] - coll_min] - 1] = collection[i]
counting_arr[collection[i] - coll_min] -= 1
return ordered
def counting_sort_string(string):
"""
>>> counting_sort_string("thisisthestring")
'eghhiiinrsssttt'
"""
return "".join([chr(i) for i in counting_sort([ord(c) for c in string])])
if __name__ == "__main__":
# Test string sort
assert counting_sort_string("thisisthestring") == "eghhiiinrsssttt"
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(counting_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/quick_sort_3_partition.py | sorts/quick_sort_3_partition.py | def quick_sort_3partition(sorting: list, left: int, right: int) -> None:
""" "
Python implementation of quick sort algorithm with 3-way partition.
The idea of 3-way quick sort is based on "Dutch National Flag algorithm".
:param sorting: sort list
:param left: left endpoint of sorting
:param right: right endpoint of sorting
:return: None
Examples:
>>> array1 = [5, -1, -1, 5, 5, 24, 0]
>>> quick_sort_3partition(array1, 0, 6)
>>> array1
[-1, -1, 0, 5, 5, 5, 24]
>>> array2 = [9, 0, 2, 6]
>>> quick_sort_3partition(array2, 0, 3)
>>> array2
[0, 2, 6, 9]
>>> array3 = []
>>> quick_sort_3partition(array3, 0, 0)
>>> array3
[]
"""
if right <= left:
return
a = i = left
b = right
pivot = sorting[left]
while i <= b:
if sorting[i] < pivot:
sorting[a], sorting[i] = sorting[i], sorting[a]
a += 1
i += 1
elif sorting[i] > pivot:
sorting[b], sorting[i] = sorting[i], sorting[b]
b -= 1
else:
i += 1
quick_sort_3partition(sorting, left, a - 1)
quick_sort_3partition(sorting, b + 1, right)
def quick_sort_lomuto_partition(sorting: list, left: int, right: int) -> None:
"""
A pure Python implementation of quick sort algorithm(in-place)
with Lomuto partition scheme:
https://en.wikipedia.org/wiki/Quicksort#Lomuto_partition_scheme
:param sorting: sort list
:param left: left endpoint of sorting
:param right: right endpoint of sorting
:return: None
Examples:
>>> nums1 = [0, 5, 3, 1, 2]
>>> quick_sort_lomuto_partition(nums1, 0, 4)
>>> nums1
[0, 1, 2, 3, 5]
>>> nums2 = []
>>> quick_sort_lomuto_partition(nums2, 0, 0)
>>> nums2
[]
>>> nums3 = [-2, 5, 0, -4]
>>> quick_sort_lomuto_partition(nums3, 0, 3)
>>> nums3
[-4, -2, 0, 5]
"""
if left < right:
pivot_index = lomuto_partition(sorting, left, right)
quick_sort_lomuto_partition(sorting, left, pivot_index - 1)
quick_sort_lomuto_partition(sorting, pivot_index + 1, right)
def lomuto_partition(sorting: list, left: int, right: int) -> int:
"""
Example:
>>> lomuto_partition([1,5,7,6], 0, 3)
2
"""
pivot = sorting[right]
store_index = left
for i in range(left, right):
if sorting[i] < pivot:
sorting[store_index], sorting[i] = sorting[i], sorting[store_index]
store_index += 1
sorting[right], sorting[store_index] = sorting[store_index], sorting[right]
return store_index
def three_way_radix_quicksort(sorting: list) -> list:
"""
Three-way radix quicksort:
https://en.wikipedia.org/wiki/Quicksort#Three-way_radix_quicksort
First divide the list into three parts.
Then recursively sort the "less than" and "greater than" partitions.
>>> three_way_radix_quicksort([])
[]
>>> three_way_radix_quicksort([1])
[1]
>>> three_way_radix_quicksort([-5, -2, 1, -2, 0, 1])
[-5, -2, -2, 0, 1, 1]
>>> three_way_radix_quicksort([1, 2, 5, 1, 2, 0, 0, 5, 2, -1])
[-1, 0, 0, 1, 1, 2, 2, 2, 5, 5]
"""
if len(sorting) <= 1:
return sorting
return (
three_way_radix_quicksort([i for i in sorting if i < sorting[0]])
+ [i for i in sorting if i == sorting[0]]
+ three_way_radix_quicksort([i for i in sorting if i > sorting[0]])
)
if __name__ == "__main__":
import doctest
doctest.testmod(verbose=True)
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
quick_sort_3partition(unsorted, 0, len(unsorted) - 1)
print(unsorted)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/quick_sort.py | sorts/quick_sort.py | """
A pure Python implementation of the quick sort algorithm
For doctests run following command:
python3 -m doctest -v quick_sort.py
For manual testing run:
python3 quick_sort.py
"""
from __future__ import annotations
from random import randrange
def quick_sort(collection: list) -> list:
"""A pure Python implementation of quicksort algorithm.
:param collection: a mutable collection of comparable items
:return: the same collection ordered in ascending order
Examples:
>>> quick_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> quick_sort([])
[]
>>> quick_sort([-2, 5, 0, -45])
[-45, -2, 0, 5]
"""
# Base case: if the collection has 0 or 1 elements, it is already sorted
if len(collection) < 2:
return collection
# Randomly select a pivot index and remove the pivot element from the collection
pivot_index = randrange(len(collection))
pivot = collection.pop(pivot_index)
# Partition the remaining elements into two groups: lesser or equal, and greater
lesser = [item for item in collection if item <= pivot]
greater = [item for item in collection if item > pivot]
# Recursively sort the lesser and greater groups, and combine with the pivot
return [*quick_sort(lesser), pivot, *quick_sort(greater)]
if __name__ == "__main__":
# Get user input and convert it into a list of integers
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
# Print the result of sorting the user-provided list
print(quick_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/odd_even_sort.py | sorts/odd_even_sort.py | """
Odd even sort implementation.
https://en.wikipedia.org/wiki/Odd%E2%80%93even_sort
"""
def odd_even_sort(input_list: list) -> list:
"""
Sort input with odd even sort.
This algorithm uses the same idea of bubblesort,
but by first dividing in two phase (odd and even).
Originally developed for use on parallel processors
with local interconnections.
:param collection: mutable ordered sequence of elements
:return: same collection in ascending order
Examples:
>>> odd_even_sort([5 , 4 ,3 ,2 ,1])
[1, 2, 3, 4, 5]
>>> odd_even_sort([])
[]
>>> odd_even_sort([-10 ,-1 ,10 ,2])
[-10, -1, 2, 10]
>>> odd_even_sort([1 ,2 ,3 ,4])
[1, 2, 3, 4]
"""
is_sorted = False
while is_sorted is False: # Until all the indices are traversed keep looping
is_sorted = True
for i in range(0, len(input_list) - 1, 2): # iterating over all even indices
if input_list[i] > input_list[i + 1]:
input_list[i], input_list[i + 1] = input_list[i + 1], input_list[i]
# swapping if elements not in order
is_sorted = False
for i in range(1, len(input_list) - 1, 2): # iterating over all odd indices
if input_list[i] > input_list[i + 1]:
input_list[i], input_list[i + 1] = input_list[i + 1], input_list[i]
# swapping if elements not in order
is_sorted = False
return input_list
if __name__ == "__main__":
print("Enter list to be sorted")
input_list = [int(x) for x in input().split()]
# inputing elements of the list in one line
sorted_list = odd_even_sort(input_list)
print("The sorted list is")
print(sorted_list)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/recursive_mergesort_array.py | sorts/recursive_mergesort_array.py | """A merge sort which accepts an array as input and recursively
splits an array in half and sorts and combines them.
"""
"""https://en.wikipedia.org/wiki/Merge_sort """
def merge(arr: list[int]) -> list[int]:
"""Return a sorted array.
>>> merge([10,9,8,7,6,5,4,3,2,1])
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> merge([1,2,3,4,5,6,7,8,9,10])
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> merge([10,22,1,2,3,9,15,23])
[1, 2, 3, 9, 10, 15, 22, 23]
>>> merge([100])
[100]
>>> merge([])
[]
"""
if len(arr) > 1:
middle_length = len(arr) // 2 # Finds the middle of the array
left_array = arr[
:middle_length
] # Creates an array of the elements in the first half.
right_array = arr[
middle_length:
] # Creates an array of the elements in the second half.
left_size = len(left_array)
right_size = len(right_array)
merge(left_array) # Starts sorting the left.
merge(right_array) # Starts sorting the right
left_index = 0 # Left Counter
right_index = 0 # Right Counter
index = 0 # Position Counter
while (
left_index < left_size and right_index < right_size
): # Runs until the lowers size of the left and right are sorted.
if left_array[left_index] < right_array[right_index]:
arr[index] = left_array[left_index]
left_index += 1
else:
arr[index] = right_array[right_index]
right_index += 1
index += 1
while (
left_index < left_size
): # Adds the left over elements in the left half of the array
arr[index] = left_array[left_index]
left_index += 1
index += 1
while (
right_index < right_size
): # Adds the left over elements in the right half of the array
arr[index] = right_array[right_index]
right_index += 1
index += 1
return arr
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/stooge_sort.py | sorts/stooge_sort.py | def stooge_sort(arr: list[int]) -> list[int]:
"""
Examples:
>>> stooge_sort([18.1, 0, -7.1, -1, 2, 2])
[-7.1, -1, 0, 2, 2, 18.1]
>>> stooge_sort([])
[]
"""
stooge(arr, 0, len(arr) - 1)
return arr
def stooge(arr: list[int], i: int, h: int) -> None:
if i >= h:
return
# If first element is smaller than the last then swap them
if arr[i] > arr[h]:
arr[i], arr[h] = arr[h], arr[i]
# If there are more than 2 elements in the array
if h - i + 1 > 2:
t = (int)((h - i + 1) / 3)
# Recursively sort first 2/3 elements
stooge(arr, i, (h - t))
# Recursively sort last 2/3 elements
stooge(arr, i + t, (h))
# Recursively sort first 2/3 elements
stooge(arr, i, (h - t))
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(stooge_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/heap_sort.py | sorts/heap_sort.py | """
A pure Python implementation of the heap sort algorithm.
"""
def heapify(unsorted: list[int], index: int, heap_size: int) -> None:
"""
:param unsorted: unsorted list containing integers numbers
:param index: index
:param heap_size: size of the heap
:return: None
>>> unsorted = [1, 4, 3, 5, 2]
>>> heapify(unsorted, 0, len(unsorted))
>>> unsorted
[4, 5, 3, 1, 2]
>>> heapify(unsorted, 0, len(unsorted))
>>> unsorted
[5, 4, 3, 1, 2]
"""
largest = index
left_index = 2 * index + 1
right_index = 2 * index + 2
if left_index < heap_size and unsorted[left_index] > unsorted[largest]:
largest = left_index
if right_index < heap_size and unsorted[right_index] > unsorted[largest]:
largest = right_index
if largest != index:
unsorted[largest], unsorted[index] = (unsorted[index], unsorted[largest])
heapify(unsorted, largest, heap_size)
def heap_sort(unsorted: list[int]) -> list[int]:
"""
A pure Python implementation of the heap sort algorithm
:param collection: a mutable ordered collection of heterogeneous comparable items
:return: the same collection ordered by ascending
Examples:
>>> heap_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> heap_sort([])
[]
>>> heap_sort([-2, -5, -45])
[-45, -5, -2]
>>> heap_sort([3, 7, 9, 28, 123, -5, 8, -30, -200, 0, 4])
[-200, -30, -5, 0, 3, 4, 7, 8, 9, 28, 123]
"""
n = len(unsorted)
for i in range(n // 2 - 1, -1, -1):
heapify(unsorted, i, n)
for i in range(n - 1, 0, -1):
unsorted[0], unsorted[i] = unsorted[i], unsorted[0]
heapify(unsorted, 0, i)
return unsorted
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
if user_input:
unsorted = [int(item) for item in user_input.split(",")]
print(f"{heap_sort(unsorted) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/comb_sort.py | sorts/comb_sort.py | """
This is pure Python implementation of comb sort algorithm.
Comb sort is a relatively simple sorting algorithm originally designed by Wlodzimierz
Dobosiewicz in 1980. It was rediscovered by Stephen Lacey and Richard Box in 1991.
Comb sort improves on bubble sort algorithm.
In bubble sort, distance (or gap) between two compared elements is always one.
Comb sort improvement is that gap can be much more than 1, in order to prevent slowing
down by small values at the end of a list.
More info on: https://en.wikipedia.org/wiki/Comb_sort
For doctests run following command:
python -m doctest -v comb_sort.py
or
python3 -m doctest -v comb_sort.py
For manual testing run:
python comb_sort.py
"""
def comb_sort(data: list) -> list:
"""Pure implementation of comb sort algorithm in Python
:param data: mutable collection with comparable items
:return: the same collection in ascending order
Examples:
>>> comb_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> comb_sort([])
[]
>>> comb_sort([99, 45, -7, 8, 2, 0, -15, 3])
[-15, -7, 0, 2, 3, 8, 45, 99]
"""
shrink_factor = 1.3
gap = len(data)
completed = False
while not completed:
# Update the gap value for a next comb
gap = int(gap / shrink_factor)
if gap <= 1:
completed = True
index = 0
while index + gap < len(data):
if data[index] > data[index + gap]:
# Swap values
data[index], data[index + gap] = data[index + gap], data[index]
completed = False
index += 1
return data
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(comb_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/tim_sort.py | sorts/tim_sort.py | def binary_search(lst, item, start, end):
if start == end:
return start if lst[start] > item else start + 1
if start > end:
return start
mid = (start + end) // 2
if lst[mid] < item:
return binary_search(lst, item, mid + 1, end)
elif lst[mid] > item:
return binary_search(lst, item, start, mid - 1)
else:
return mid
def insertion_sort(lst):
length = len(lst)
for index in range(1, length):
value = lst[index]
pos = binary_search(lst, value, 0, index - 1)
lst = [*lst[:pos], value, *lst[pos:index], *lst[index + 1 :]]
return lst
def merge(left, right):
if not left:
return right
if not right:
return left
if left[0] < right[0]:
return [left[0], *merge(left[1:], right)]
return [right[0], *merge(left, right[1:])]
def tim_sort(lst):
"""
>>> tim_sort("Python")
['P', 'h', 'n', 'o', 't', 'y']
>>> tim_sort((1.1, 1, 0, -1, -1.1))
[-1.1, -1, 0, 1, 1.1]
>>> tim_sort(list(reversed(list(range(7)))))
[0, 1, 2, 3, 4, 5, 6]
>>> tim_sort([3, 2, 1]) == insertion_sort([3, 2, 1])
True
>>> tim_sort([3, 2, 1]) == sorted([3, 2, 1])
True
"""
length = len(lst)
runs, sorted_runs = [], []
new_run = [lst[0]]
sorted_array = []
i = 1
while i < length:
if lst[i] < lst[i - 1]:
runs.append(new_run)
new_run = [lst[i]]
else:
new_run.append(lst[i])
i += 1
runs.append(new_run)
for run in runs:
sorted_runs.append(insertion_sort(run))
for run in sorted_runs:
sorted_array = merge(sorted_array, run)
return sorted_array
def main():
lst = [5, 9, 10, 3, -4, 5, 178, 92, 46, -18, 0, 7]
sorted_lst = tim_sort(lst)
print(sorted_lst)
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/external_sort.py | sorts/external_sort.py | #!/usr/bin/env python
#
# Sort large text files in a minimum amount of memory
#
import argparse
import os
class FileSplitter:
BLOCK_FILENAME_FORMAT = "block_{0}.dat"
def __init__(self, filename):
self.filename = filename
self.block_filenames = []
def write_block(self, data, block_number):
filename = self.BLOCK_FILENAME_FORMAT.format(block_number)
with open(filename, "w") as file:
file.write(data)
self.block_filenames.append(filename)
def get_block_filenames(self):
return self.block_filenames
def split(self, block_size, sort_key=None):
i = 0
with open(self.filename) as file:
while True:
lines = file.readlines(block_size)
if lines == []:
break
if sort_key is None:
lines.sort()
else:
lines.sort(key=sort_key)
self.write_block("".join(lines), i)
i += 1
def cleanup(self):
map(os.remove, self.block_filenames)
class NWayMerge:
def select(self, choices):
min_index = -1
min_str = None
for i in range(len(choices)):
if min_str is None or choices[i] < min_str:
min_index = i
return min_index
class FilesArray:
def __init__(self, files):
self.files = files
self.empty = set()
self.num_buffers = len(files)
self.buffers = dict.fromkeys(range(self.num_buffers))
def get_dict(self):
return {
i: self.buffers[i] for i in range(self.num_buffers) if i not in self.empty
}
def refresh(self):
for i in range(self.num_buffers):
if self.buffers[i] is None and i not in self.empty:
self.buffers[i] = self.files[i].readline()
if self.buffers[i] == "":
self.empty.add(i)
self.files[i].close()
return len(self.empty) != self.num_buffers
def unshift(self, index):
value = self.buffers[index]
self.buffers[index] = None
return value
class FileMerger:
def __init__(self, merge_strategy):
self.merge_strategy = merge_strategy
def merge(self, filenames, outfilename, buffer_size):
buffers = FilesArray(self.get_file_handles(filenames, buffer_size))
with open(outfilename, "w", buffer_size) as outfile:
while buffers.refresh():
min_index = self.merge_strategy.select(buffers.get_dict())
outfile.write(buffers.unshift(min_index))
def get_file_handles(self, filenames, buffer_size):
files = {}
for i in range(len(filenames)):
files[i] = open(filenames[i], "r", buffer_size) # noqa: UP015
return files
class ExternalSort:
def __init__(self, block_size):
self.block_size = block_size
def sort(self, filename, sort_key=None):
num_blocks = self.get_number_blocks(filename, self.block_size)
splitter = FileSplitter(filename)
splitter.split(self.block_size, sort_key)
merger = FileMerger(NWayMerge())
buffer_size = self.block_size / (num_blocks + 1)
merger.merge(splitter.get_block_filenames(), filename + ".out", buffer_size)
splitter.cleanup()
def get_number_blocks(self, filename, block_size):
return (os.stat(filename).st_size / block_size) + 1
def parse_memory(string):
if string[-1].lower() == "k":
return int(string[:-1]) * 1024
elif string[-1].lower() == "m":
return int(string[:-1]) * 1024 * 1024
elif string[-1].lower() == "g":
return int(string[:-1]) * 1024 * 1024 * 1024
else:
return int(string)
def main():
parser = argparse.ArgumentParser()
parser.add_argument(
"-m", "--mem", help="amount of memory to use for sorting", default="100M"
)
parser.add_argument(
"filename", metavar="<filename>", nargs=1, help="name of file to sort"
)
args = parser.parse_args()
sorter = ExternalSort(parse_memory(args.mem))
sorter.sort(args.filename[0])
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/stalin_sort.py | sorts/stalin_sort.py | """
Stalin Sort algorithm: Removes elements that are out of order.
Elements that are not greater than or equal to the previous element are discarded.
Reference: https://medium.com/@kaweendra/the-ultimate-sorting-algorithm-6513d6968420
"""
def stalin_sort(sequence: list[int]) -> list[int]:
"""
Sorts a list using the Stalin sort algorithm.
>>> stalin_sort([4, 3, 5, 2, 1, 7])
[4, 5, 7]
>>> stalin_sort([1, 2, 3, 4])
[1, 2, 3, 4]
>>> stalin_sort([4, 5, 5, 2, 3])
[4, 5, 5]
>>> stalin_sort([6, 11, 12, 4, 1, 5])
[6, 11, 12]
>>> stalin_sort([5, 0, 4, 3])
[5]
>>> stalin_sort([5, 4, 3, 2, 1])
[5]
>>> stalin_sort([1, 2, 3, 4, 5])
[1, 2, 3, 4, 5]
>>> stalin_sort([1, 2, 8, 7, 6])
[1, 2, 8]
"""
result = [sequence[0]]
for element in sequence[1:]:
if element >= result[-1]:
result.append(element)
return result
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/patience_sort.py | sorts/patience_sort.py | from __future__ import annotations
from bisect import bisect_left
from functools import total_ordering
from heapq import merge
"""
A pure Python implementation of the patience sort algorithm
For more information: https://en.wikipedia.org/wiki/Patience_sorting
This algorithm is based on the card game patience
For doctests run following command:
python3 -m doctest -v patience_sort.py
For manual testing run:
python3 patience_sort.py
"""
@total_ordering
class Stack(list):
def __lt__(self, other):
return self[-1] < other[-1]
def __eq__(self, other):
return self[-1] == other[-1]
def patience_sort(collection: list) -> list:
"""A pure implementation of patience sort algorithm in Python
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> patience_sort([1, 9, 5, 21, 17, 6])
[1, 5, 6, 9, 17, 21]
>>> patience_sort([])
[]
>>> patience_sort([-3, -17, -48])
[-48, -17, -3]
"""
stacks: list[Stack] = []
# sort into stacks
for element in collection:
new_stacks = Stack([element])
i = bisect_left(stacks, new_stacks)
if i != len(stacks):
stacks[i].append(element)
else:
stacks.append(new_stacks)
# use a heap-based merge to merge stack efficiently
collection[:] = merge(*(reversed(stack) for stack in stacks))
return collection
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(patience_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/bogo_sort.py | sorts/bogo_sort.py | """
This is a pure Python implementation of the bogosort algorithm,
also known as permutation sort, stupid sort, slowsort, shotgun sort, or monkey sort.
Bogosort generates random permutations until it guesses the correct one.
More info on: https://en.wikipedia.org/wiki/Bogosort
For doctests run following command:
python -m doctest -v bogo_sort.py
or
python3 -m doctest -v bogo_sort.py
For manual testing run:
python bogo_sort.py
"""
import random
def bogo_sort(collection):
"""Pure implementation of the bogosort algorithm in Python
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> bogo_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> bogo_sort([])
[]
>>> bogo_sort([-2, -5, -45])
[-45, -5, -2]
"""
def is_sorted(collection):
for i in range(len(collection) - 1):
if collection[i] > collection[i + 1]:
return False
return True
while not is_sorted(collection):
random.shuffle(collection)
return collection
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(bogo_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/insertion_sort.py | sorts/insertion_sort.py | """
A pure Python implementation of the insertion sort algorithm
This algorithm sorts a collection by comparing adjacent elements.
When it finds that order is not respected, it moves the element compared
backward until the order is correct. It then goes back directly to the
element's initial position resuming forward comparison.
For doctests run following command:
python3 -m doctest -v insertion_sort.py
For manual testing run:
python3 insertion_sort.py
"""
from collections.abc import MutableSequence
from typing import Any, Protocol, TypeVar
class Comparable(Protocol):
def __lt__(self, other: Any, /) -> bool: ...
T = TypeVar("T", bound=Comparable)
def insertion_sort[T: Comparable](collection: MutableSequence[T]) -> MutableSequence[T]:
"""A pure Python implementation of the insertion sort algorithm
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> insertion_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> insertion_sort([]) == sorted([])
True
>>> insertion_sort([-2, -5, -45]) == sorted([-2, -5, -45])
True
>>> insertion_sort(['d', 'a', 'b', 'e', 'c']) == sorted(['d', 'a', 'b', 'e', 'c'])
True
>>> import random
>>> collection = random.sample(range(-50, 50), 100)
>>> insertion_sort(collection) == sorted(collection)
True
>>> import string
>>> collection = random.choices(string.ascii_letters + string.digits, k=100)
>>> insertion_sort(collection) == sorted(collection)
True
"""
for insert_index in range(1, len(collection)):
insert_value = collection[insert_index]
while insert_index > 0 and insert_value < collection[insert_index - 1]:
collection[insert_index] = collection[insert_index - 1]
insert_index -= 1
collection[insert_index] = insert_value
return collection
if __name__ == "__main__":
from doctest import testmod
testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(f"{insertion_sort(unsorted) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/shell_sort.py | sorts/shell_sort.py | """
https://en.wikipedia.org/wiki/Shellsort#Pseudocode
"""
def shell_sort(collection: list[int]) -> list[int]:
"""Pure implementation of shell sort algorithm in Python
:param collection: Some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
>>> shell_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> shell_sort([])
[]
>>> shell_sort([-2, -5, -45])
[-45, -5, -2]
"""
# Marcin Ciura's gap sequence
gaps = [701, 301, 132, 57, 23, 10, 4, 1]
for gap in gaps:
for i in range(gap, len(collection)):
insert_value = collection[i]
j = i
while j >= gap and collection[j - gap] > insert_value:
collection[j] = collection[j - gap]
j -= gap
if j != i:
collection[j] = insert_value
return collection
if __name__ == "__main__":
from doctest import testmod
testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(shell_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/pigeonhole_sort.py | sorts/pigeonhole_sort.py | # Python program to implement Pigeonhole Sorting in python
# Algorithm for the pigeonhole sorting
def pigeonhole_sort(a):
"""
>>> a = [8, 3, 2, 7, 4, 6, 8]
>>> b = sorted(a) # a nondestructive sort
>>> pigeonhole_sort(a) # a destructive sort
>>> a == b
True
"""
# size of range of values in the list (ie, number of pigeonholes we need)
min_val = min(a) # min() finds the minimum value
max_val = max(a) # max() finds the maximum value
size = max_val - min_val + 1 # size is difference of max and min values plus one
# list of pigeonholes of size equal to the variable size
holes = [0] * size
# Populate the pigeonholes.
for x in a:
assert isinstance(x, int), "integers only please"
holes[x - min_val] += 1
# Putting the elements back into the array in an order.
i = 0
for count in range(size):
while holes[count] > 0:
holes[count] -= 1
a[i] = count + min_val
i += 1
def main():
a = [8, 3, 2, 7, 4, 6, 8]
pigeonhole_sort(a)
print("Sorted order is:", " ".join(a))
if __name__ == "__main__":
main()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/recursive_insertion_sort.py | sorts/recursive_insertion_sort.py | """
A recursive implementation of the insertion sort algorithm
"""
from __future__ import annotations
def rec_insertion_sort(collection: list, n: int):
"""
Given a collection of numbers and its length, sorts the collections
in ascending order
:param collection: A mutable collection of comparable elements
:param n: The length of collections
>>> col = [1, 2, 1]
>>> rec_insertion_sort(col, len(col))
>>> col
[1, 1, 2]
>>> col = [2, 1, 0, -1, -2]
>>> rec_insertion_sort(col, len(col))
>>> col
[-2, -1, 0, 1, 2]
>>> col = [1]
>>> rec_insertion_sort(col, len(col))
>>> col
[1]
"""
# Checks if the entire collection has been sorted
if len(collection) <= 1 or n <= 1:
return
insert_next(collection, n - 1)
rec_insertion_sort(collection, n - 1)
def insert_next(collection: list, index: int):
"""
Inserts the '(index-1)th' element into place
>>> col = [3, 2, 4, 2]
>>> insert_next(col, 1)
>>> col
[2, 3, 4, 2]
>>> col = [3, 2, 3]
>>> insert_next(col, 2)
>>> col
[3, 2, 3]
>>> col = []
>>> insert_next(col, 1)
>>> col
[]
"""
# Checks order between adjacent elements
if index >= len(collection) or collection[index - 1] <= collection[index]:
return
# Swaps adjacent elements since they are not in ascending order
collection[index - 1], collection[index] = (
collection[index],
collection[index - 1],
)
insert_next(collection, index + 1)
if __name__ == "__main__":
numbers = input("Enter integers separated by spaces: ")
number_list: list[int] = [int(num) for num in numbers.split()]
rec_insertion_sort(number_list, len(number_list))
print(number_list)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/bitonic_sort.py | sorts/bitonic_sort.py | """
Python program for Bitonic Sort.
Note that this program works only when size of input is a power of 2.
"""
from __future__ import annotations
def comp_and_swap(array: list[int], index1: int, index2: int, direction: int) -> None:
"""Compare the value at given index1 and index2 of the array and swap them as per
the given direction.
The parameter direction indicates the sorting direction, ASCENDING(1) or
DESCENDING(0); if (a[i] > a[j]) agrees with the direction, then a[i] and a[j] are
interchanged.
>>> arr = [12, 42, -21, 1]
>>> comp_and_swap(arr, 1, 2, 1)
>>> arr
[12, -21, 42, 1]
>>> comp_and_swap(arr, 1, 2, 0)
>>> arr
[12, 42, -21, 1]
>>> comp_and_swap(arr, 0, 3, 1)
>>> arr
[1, 42, -21, 12]
>>> comp_and_swap(arr, 0, 3, 0)
>>> arr
[12, 42, -21, 1]
"""
if (direction == 1 and array[index1] > array[index2]) or (
direction == 0 and array[index1] < array[index2]
):
array[index1], array[index2] = array[index2], array[index1]
def bitonic_merge(array: list[int], low: int, length: int, direction: int) -> None:
"""
It recursively sorts a bitonic sequence in ascending order, if direction = 1, and in
descending if direction = 0.
The sequence to be sorted starts at index position low, the parameter length is the
number of elements to be sorted.
>>> arr = [12, 42, -21, 1]
>>> bitonic_merge(arr, 0, 4, 1)
>>> arr
[-21, 1, 12, 42]
>>> bitonic_merge(arr, 0, 4, 0)
>>> arr
[42, 12, 1, -21]
"""
if length > 1:
middle = int(length / 2)
for i in range(low, low + middle):
comp_and_swap(array, i, i + middle, direction)
bitonic_merge(array, low, middle, direction)
bitonic_merge(array, low + middle, middle, direction)
def bitonic_sort(array: list[int], low: int, length: int, direction: int) -> None:
"""
This function first produces a bitonic sequence by recursively sorting its two
halves in opposite sorting orders, and then calls bitonic_merge to make them in the
same order.
>>> arr = [12, 34, 92, -23, 0, -121, -167, 145]
>>> bitonic_sort(arr, 0, 8, 1)
>>> arr
[-167, -121, -23, 0, 12, 34, 92, 145]
>>> bitonic_sort(arr, 0, 8, 0)
>>> arr
[145, 92, 34, 12, 0, -23, -121, -167]
"""
if length > 1:
middle = int(length / 2)
bitonic_sort(array, low, middle, 1)
bitonic_sort(array, low + middle, middle, 0)
bitonic_merge(array, low, length, direction)
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item.strip()) for item in user_input.split(",")]
bitonic_sort(unsorted, 0, len(unsorted), 1)
print("\nSorted array in ascending order is: ", end="")
print(*unsorted, sep=", ")
bitonic_merge(unsorted, 0, len(unsorted), 0)
print("Sorted array in descending order is: ", end="")
print(*unsorted, sep=", ")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/odd_even_transposition_single_threaded.py | sorts/odd_even_transposition_single_threaded.py | """
Source: https://en.wikipedia.org/wiki/Odd%E2%80%93even_sort
This is a non-parallelized implementation of odd-even transposition sort.
Normally the swaps in each set happen simultaneously, without that the algorithm
is no better than bubble sort.
"""
def odd_even_transposition(arr: list) -> list:
"""
>>> odd_even_transposition([5, 4, 3, 2, 1])
[1, 2, 3, 4, 5]
>>> odd_even_transposition([13, 11, 18, 0, -1])
[-1, 0, 11, 13, 18]
>>> odd_even_transposition([-.1, 1.1, .1, -2.9])
[-2.9, -0.1, 0.1, 1.1]
"""
arr_size = len(arr)
for _ in range(arr_size):
for i in range(_ % 2, arr_size - 1, 2):
if arr[i + 1] < arr[i]:
arr[i], arr[i + 1] = arr[i + 1], arr[i]
return arr
if __name__ == "__main__":
arr = list(range(10, 0, -1))
print(f"Original: {arr}. Sorted: {odd_even_transposition(arr)}")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/bucket_sort.py | sorts/bucket_sort.py | #!/usr/bin/env python3
"""
Illustrate how to implement bucket sort algorithm.
Author: OMKAR PATHAK
This program will illustrate how to implement bucket sort algorithm
Wikipedia says: Bucket sort, or bin sort, is a sorting algorithm that works
by distributing the elements of an array into a number of buckets.
Each bucket is then sorted individually, either using a different sorting
algorithm, or by recursively applying the bucket sorting algorithm. It is a
distribution sort, and is a cousin of radix sort in the most to least
significant digit flavour.
Bucket sort is a generalization of pigeonhole sort. Bucket sort can be
implemented with comparisons and therefore can also be considered a
comparison sort algorithm. The computational complexity estimates involve the
number of buckets.
Time Complexity of Solution:
Worst case scenario occurs when all the elements are placed in a single bucket.
The overall performance would then be dominated by the algorithm used to sort each
bucket. In this case, O(n log n), because of TimSort
Average Case O(n + (n^2)/k + k), where k is the number of buckets
If k = O(n), time complexity is O(n)
Source: https://en.wikipedia.org/wiki/Bucket_sort
"""
from __future__ import annotations
def bucket_sort(my_list: list, bucket_count: int = 10) -> list:
"""
>>> data = [-1, 2, -5, 0]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [9, 8, 7, 6, -12]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [.4, 1.2, .1, .2, -.9]
>>> bucket_sort(data) == sorted(data)
True
>>> bucket_sort([]) == sorted([])
True
>>> data = [-1e10, 1e10]
>>> bucket_sort(data) == sorted(data)
True
>>> import random
>>> collection = random.sample(range(-50, 50), 50)
>>> bucket_sort(collection) == sorted(collection)
True
>>> data = [1, 2, 2, 1, 1, 3]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [5, 5, 5, 5, 5]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [1000, -1000, 500, -500, 0]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [5.5, 2.2, -1.1, 3.3, 0.0]
>>> bucket_sort(data) == sorted(data)
True
>>> bucket_sort([1]) == [1]
True
>>> data = [-1.1, -1.5, -3.4, 2.5, 3.6, -3.3]
>>> bucket_sort(data) == sorted(data)
True
>>> data = [9, 2, 7, 1, 5]
>>> bucket_sort(data) == sorted(data)
True
"""
if len(my_list) == 0 or bucket_count <= 0:
return []
min_value, max_value = min(my_list), max(my_list)
if min_value == max_value:
return my_list
bucket_size = (max_value - min_value) / bucket_count
buckets: list[list] = [[] for _ in range(bucket_count)]
for val in my_list:
index = min(int((val - min_value) / bucket_size), bucket_count - 1)
buckets[index].append(val)
return [val for bucket in buckets for val in sorted(bucket)]
if __name__ == "__main__":
from doctest import testmod
testmod()
assert bucket_sort([4, 5, 3, 2, 1]) == [1, 2, 3, 4, 5]
assert bucket_sort([0, 1, -10, 15, 2, -2]) == [-10, -2, 0, 1, 2, 15]
assert bucket_sort([1.1, 1.2, -1.2, 0, 2.4]) == [-1.2, 0, 1.1, 1.2, 2.4]
assert bucket_sort([5, 5, 5, 5, 5]) == [5, 5, 5, 5, 5]
assert bucket_sort([-5, -1, -6, -2]) == [-6, -5, -2, -1]
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/dutch_national_flag_sort.py | sorts/dutch_national_flag_sort.py | """
A pure implementation of Dutch national flag (DNF) sort algorithm in Python.
Dutch National Flag algorithm is an algorithm originally designed by Edsger Dijkstra.
It is the most optimal sort for 3 unique values (eg. 0, 1, 2) in a sequence. DNF can
sort a sequence of n size with [0 <= a[i] <= 2] at guaranteed O(n) complexity in a
single pass.
The flag of the Netherlands consists of three colors: white, red, and blue.
The task is to randomly arrange balls of white, red, and blue in such a way that balls
of the same color are placed together. DNF sorts a sequence of 0, 1, and 2's in linear
time that does not consume any extra space. This algorithm can be implemented only on
a sequence that contains three unique elements.
1) Time complexity is O(n).
2) Space complexity is O(1).
More info on: https://en.wikipedia.org/wiki/Dutch_national_flag_problem
For doctests run following command:
python3 -m doctest -v dutch_national_flag_sort.py
For manual testing run:
python dnf_sort.py
"""
# Python program to sort a sequence containing only 0, 1 and 2 in a single pass.
red = 0 # The first color of the flag.
white = 1 # The second color of the flag.
blue = 2 # The third color of the flag.
colors = (red, white, blue)
def dutch_national_flag_sort(sequence: list) -> list:
"""
A pure Python implementation of Dutch National Flag sort algorithm.
:param data: 3 unique integer values (e.g., 0, 1, 2) in an sequence
:return: The same collection in ascending order
>>> dutch_national_flag_sort([])
[]
>>> dutch_national_flag_sort([0])
[0]
>>> dutch_national_flag_sort([2, 1, 0, 0, 1, 2])
[0, 0, 1, 1, 2, 2]
>>> dutch_national_flag_sort([0, 1, 1, 0, 1, 2, 1, 2, 0, 0, 0, 1])
[0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2]
>>> dutch_national_flag_sort("abacab")
Traceback (most recent call last):
...
ValueError: The elements inside the sequence must contains only (0, 1, 2) values
>>> dutch_national_flag_sort("Abacab")
Traceback (most recent call last):
...
ValueError: The elements inside the sequence must contains only (0, 1, 2) values
>>> dutch_national_flag_sort([3, 2, 3, 1, 3, 0, 3])
Traceback (most recent call last):
...
ValueError: The elements inside the sequence must contains only (0, 1, 2) values
>>> dutch_national_flag_sort([-1, 2, -1, 1, -1, 0, -1])
Traceback (most recent call last):
...
ValueError: The elements inside the sequence must contains only (0, 1, 2) values
>>> dutch_national_flag_sort([1.1, 2, 1.1, 1, 1.1, 0, 1.1])
Traceback (most recent call last):
...
ValueError: The elements inside the sequence must contains only (0, 1, 2) values
"""
if not sequence:
return []
if len(sequence) == 1:
return list(sequence)
low = 0
high = len(sequence) - 1
mid = 0
while mid <= high:
if sequence[mid] == colors[0]:
sequence[low], sequence[mid] = sequence[mid], sequence[low]
low += 1
mid += 1
elif sequence[mid] == colors[1]:
mid += 1
elif sequence[mid] == colors[2]:
sequence[mid], sequence[high] = sequence[high], sequence[mid]
high -= 1
else:
msg = f"The elements inside the sequence must contains only {colors} values"
raise ValueError(msg)
return sequence
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by commas:\n").strip()
unsorted = [int(item.strip()) for item in user_input.split(",")]
print(f"{dutch_national_flag_sort(unsorted)}")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/radix_sort.py | sorts/radix_sort.py | """
This is a pure Python implementation of the radix sort algorithm
Source: https://en.wikipedia.org/wiki/Radix_sort
"""
from __future__ import annotations
RADIX = 10
def radix_sort(list_of_ints: list[int]) -> list[int]:
"""
Examples:
>>> radix_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> radix_sort(list(range(15))) == sorted(range(15))
True
>>> radix_sort(list(range(14,-1,-1))) == sorted(range(15))
True
>>> radix_sort([1,100,10,1000]) == sorted([1,100,10,1000])
True
"""
placement = 1
max_digit = max(list_of_ints)
while placement <= max_digit:
# declare and initialize empty buckets
buckets: list[list] = [[] for _ in range(RADIX)]
# split list_of_ints between the buckets
for i in list_of_ints:
tmp = int((i / placement) % RADIX)
buckets[tmp].append(i)
# put each buckets' contents into list_of_ints
a = 0
for b in range(RADIX):
for i in buckets[b]:
list_of_ints[a] = i
a += 1
# move to next
placement *= RADIX
return list_of_ints
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/circle_sort.py | sorts/circle_sort.py | """
This is a Python implementation of the circle sort algorithm
For doctests run following command:
python3 -m doctest -v circle_sort.py
For manual testing run:
python3 circle_sort.py
"""
def circle_sort(collection: list) -> list:
"""A pure Python implementation of circle sort algorithm
:param collection: a mutable collection of comparable items in any order
:return: the same collection in ascending order
Examples:
>>> circle_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> circle_sort([])
[]
>>> circle_sort([-2, 5, 0, -45])
[-45, -2, 0, 5]
>>> collections = ([], [0, 5, 3, 2, 2], [-2, 5, 0, -45])
>>> all(sorted(collection) == circle_sort(collection) for collection in collections)
True
"""
if len(collection) < 2:
return collection
def circle_sort_util(collection: list, low: int, high: int) -> bool:
"""
>>> arr = [5,4,3,2,1]
>>> circle_sort_util(lst, 0, 2)
True
>>> arr
[3, 4, 5, 2, 1]
"""
swapped = False
if low == high:
return swapped
left = low
right = high
while left < right:
if collection[left] > collection[right]:
collection[left], collection[right] = (
collection[right],
collection[left],
)
swapped = True
left += 1
right -= 1
if left == right and collection[left] > collection[right + 1]:
collection[left], collection[right + 1] = (
collection[right + 1],
collection[left],
)
swapped = True
mid = low + int((high - low) / 2)
left_swap = circle_sort_util(collection, low, mid)
right_swap = circle_sort_util(collection, mid + 1, high)
return swapped or left_swap or right_swap
is_not_sorted = True
while is_not_sorted is True:
is_not_sorted = circle_sort_util(collection, 0, len(collection) - 1)
return collection
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(circle_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/natural_sort.py | sorts/natural_sort.py | from __future__ import annotations
import re
def natural_sort(input_list: list[str]) -> list[str]:
"""
Sort the given list of strings in the way that humans expect.
The normal Python sort algorithm sorts lexicographically,
so you might not get the results that you expect...
>>> example1 = ['2 ft 7 in', '1 ft 5 in', '10 ft 2 in', '2 ft 11 in', '7 ft 6 in']
>>> sorted(example1)
['1 ft 5 in', '10 ft 2 in', '2 ft 11 in', '2 ft 7 in', '7 ft 6 in']
>>> # The natural sort algorithm sort based on meaning and not computer code point.
>>> natural_sort(example1)
['1 ft 5 in', '2 ft 7 in', '2 ft 11 in', '7 ft 6 in', '10 ft 2 in']
>>> example2 = ['Elm11', 'Elm12', 'Elm2', 'elm0', 'elm1', 'elm10', 'elm13', 'elm9']
>>> sorted(example2)
['Elm11', 'Elm12', 'Elm2', 'elm0', 'elm1', 'elm10', 'elm13', 'elm9']
>>> natural_sort(example2)
['elm0', 'elm1', 'Elm2', 'elm9', 'elm10', 'Elm11', 'Elm12', 'elm13']
"""
def alphanum_key(key):
return [int(s) if s.isdigit() else s.lower() for s in re.split("([0-9]+)", key)]
return sorted(input_list, key=alphanum_key)
if __name__ == "__main__":
import doctest
doctest.testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/topological_sort.py | sorts/topological_sort.py | """Topological Sort."""
# a
# / \
# b c
# / \
# d e
edges: dict[str, list[str]] = {
"a": ["c", "b"],
"b": ["d", "e"],
"c": [],
"d": [],
"e": [],
}
vertices: list[str] = ["a", "b", "c", "d", "e"]
def topological_sort(start: str, visited: list[str], sort: list[str]) -> list[str]:
"""Perform topological sort on a directed acyclic graph."""
current = start
# add current to visited
visited.append(current)
neighbors = edges[current]
for neighbor in neighbors:
# if neighbor not in visited, visit
if neighbor not in visited:
sort = topological_sort(neighbor, visited, sort)
# if all neighbors visited add current to sort
sort.append(current)
# if all vertices haven't been visited select a new one to visit
if len(visited) != len(vertices):
for vertice in vertices:
if vertice not in visited:
sort = topological_sort(vertice, visited, sort)
# return sort
return sort
if __name__ == "__main__":
sort = topological_sort("a", [], [])
print(sort)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/pancake_sort.py | sorts/pancake_sort.py | """
This is a pure Python implementation of the pancake sort algorithm
For doctests run following command:
python3 -m doctest -v pancake_sort.py
or
python -m doctest -v pancake_sort.py
For manual testing run:
python pancake_sort.py
"""
def pancake_sort(arr):
"""Sort Array with Pancake Sort.
:param arr: Collection containing comparable items
:return: Collection ordered in ascending order of items
Examples:
>>> pancake_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> pancake_sort([])
[]
>>> pancake_sort([-2, -5, -45])
[-45, -5, -2]
"""
cur = len(arr)
while cur > 1:
# Find the maximum number in arr
mi = arr.index(max(arr[0:cur]))
# Reverse from 0 to mi
arr = arr[mi::-1] + arr[mi + 1 : len(arr)]
# Reverse whole list
arr = arr[cur - 1 :: -1] + arr[cur : len(arr)]
cur -= 1
return arr
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(pancake_sort(unsorted))
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/slowsort.py | sorts/slowsort.py | """
Slowsort is a sorting algorithm. It is of humorous nature and not useful.
It's based on the principle of multiply and surrender,
a tongue-in-cheek joke of divide and conquer.
It was published in 1986 by Andrei Broder and Jorge Stolfi
in their paper Pessimal Algorithms and Simplexity Analysis
(a parody of optimal algorithms and complexity analysis).
Source: https://en.wikipedia.org/wiki/Slowsort
"""
from __future__ import annotations
def slowsort(sequence: list, start: int | None = None, end: int | None = None) -> None:
"""
Sorts sequence[start..end] (both inclusive) in-place.
start defaults to 0 if not given.
end defaults to len(sequence) - 1 if not given.
It returns None.
>>> seq = [1, 6, 2, 5, 3, 4, 4, 5]; slowsort(seq); seq
[1, 2, 3, 4, 4, 5, 5, 6]
>>> seq = []; slowsort(seq); seq
[]
>>> seq = [2]; slowsort(seq); seq
[2]
>>> seq = [1, 2, 3, 4]; slowsort(seq); seq
[1, 2, 3, 4]
>>> seq = [4, 3, 2, 1]; slowsort(seq); seq
[1, 2, 3, 4]
>>> seq = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]; slowsort(seq, 2, 7); seq
[9, 8, 2, 3, 4, 5, 6, 7, 1, 0]
>>> seq = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]; slowsort(seq, end = 4); seq
[5, 6, 7, 8, 9, 4, 3, 2, 1, 0]
>>> seq = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]; slowsort(seq, start = 5); seq
[9, 8, 7, 6, 5, 0, 1, 2, 3, 4]
"""
if start is None:
start = 0
if end is None:
end = len(sequence) - 1
if start >= end:
return
mid = (start + end) // 2
slowsort(sequence, start, mid)
slowsort(sequence, mid + 1, end)
if sequence[end] < sequence[mid]:
sequence[end], sequence[mid] = sequence[mid], sequence[end]
slowsort(sequence, start, end - 1)
if __name__ == "__main__":
from doctest import testmod
testmod()
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/selection_sort.py | sorts/selection_sort.py | def selection_sort(collection: list[int]) -> list[int]:
"""
Sorts a list in ascending order using the selection sort algorithm.
:param collection: A list of integers to be sorted.
:return: The sorted list.
Examples:
>>> selection_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> selection_sort([])
[]
>>> selection_sort([-2, -5, -45])
[-45, -5, -2]
"""
length = len(collection)
for i in range(length - 1):
min_index = i
for k in range(i + 1, length):
if collection[k] < collection[min_index]:
min_index = k
if min_index != i:
collection[i], collection[min_index] = collection[min_index], collection[i]
return collection
if __name__ == "__main__":
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
sorted_list = selection_sort(unsorted)
print("Sorted List:", sorted_list)
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/cyclic_sort.py | sorts/cyclic_sort.py | """
This is a pure Python implementation of the Cyclic Sort algorithm.
For doctests run following command:
python -m doctest -v cyclic_sort.py
or
python3 -m doctest -v cyclic_sort.py
For manual testing run:
python cyclic_sort.py
or
python3 cyclic_sort.py
"""
def cyclic_sort(nums: list[int]) -> list[int]:
"""
Sorts the input list of n integers from 1 to n in-place
using the Cyclic Sort algorithm.
:param nums: List of n integers from 1 to n to be sorted.
:return: The same list sorted in ascending order.
Time complexity: O(n), where n is the number of integers in the list.
Examples:
>>> cyclic_sort([])
[]
>>> cyclic_sort([3, 5, 2, 1, 4])
[1, 2, 3, 4, 5]
"""
# Perform cyclic sort
index = 0
while index < len(nums):
# Calculate the correct index for the current element
correct_index = nums[index] - 1
# If the current element is not at its correct position,
# swap it with the element at its correct index
if index != correct_index:
nums[index], nums[correct_index] = nums[correct_index], nums[index]
else:
# If the current element is already in its correct position,
# move to the next element
index += 1
return nums
if __name__ == "__main__":
import doctest
doctest.testmod()
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(*cyclic_sort(unsorted), sep=",")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/__init__.py | sorts/__init__.py | python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false | |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/merge_sort.py | sorts/merge_sort.py | """
This is a pure Python implementation of the merge sort algorithm.
For doctests run following command:
python -m doctest -v merge_sort.py
or
python3 -m doctest -v merge_sort.py
For manual testing run:
python merge_sort.py
"""
def merge_sort(collection: list) -> list:
"""
Sorts a list using the merge sort algorithm.
:param collection: A mutable ordered collection with comparable items.
:return: The same collection ordered in ascending order.
Time Complexity: O(n log n)
Space Complexity: O(n)
Examples:
>>> merge_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> merge_sort([])
[]
>>> merge_sort([-2, -5, -45])
[-45, -5, -2]
"""
def merge(left: list, right: list) -> list:
"""
Merge two sorted lists into a single sorted list.
:param left: Left collection
:param right: Right collection
:return: Merged result
"""
result = []
while left and right:
result.append(left.pop(0) if left[0] <= right[0] else right.pop(0))
result.extend(left)
result.extend(right)
return result
if len(collection) <= 1:
return collection
mid_index = len(collection) // 2
return merge(merge_sort(collection[:mid_index]), merge_sort(collection[mid_index:]))
if __name__ == "__main__":
import doctest
doctest.testmod()
try:
user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
sorted_list = merge_sort(unsorted)
print(*sorted_list, sep=",")
except ValueError:
print("Invalid input. Please enter valid integers separated by commas.")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/cycle_sort.py | sorts/cycle_sort.py | """
Code contributed by Honey Sharma
Source: https://en.wikipedia.org/wiki/Cycle_sort
"""
def cycle_sort(array: list) -> list:
"""
>>> cycle_sort([4, 3, 2, 1])
[1, 2, 3, 4]
>>> cycle_sort([-4, 20, 0, -50, 100, -1])
[-50, -4, -1, 0, 20, 100]
>>> cycle_sort([-.1, -.2, 1.3, -.8])
[-0.8, -0.2, -0.1, 1.3]
>>> cycle_sort([])
[]
"""
array_len = len(array)
for cycle_start in range(array_len - 1):
item = array[cycle_start]
pos = cycle_start
for i in range(cycle_start + 1, array_len):
if array[i] < item:
pos += 1
if pos == cycle_start:
continue
while item == array[pos]:
pos += 1
array[pos], item = item, array[pos]
while pos != cycle_start:
pos = cycle_start
for i in range(cycle_start + 1, array_len):
if array[i] < item:
pos += 1
while item == array[pos]:
pos += 1
array[pos], item = item, array[pos]
return array
if __name__ == "__main__":
assert cycle_sort([4, 5, 3, 2, 1]) == [1, 2, 3, 4, 5]
assert cycle_sort([0, 1, -10, 15, 2, -2]) == [-10, -2, 0, 1, 2, 15]
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
TheAlgorithms/Python | https://github.com/TheAlgorithms/Python/blob/2c15b8c54eb8130e83640fe1d911c10eb6cd70d4/sorts/tree_sort.py | sorts/tree_sort.py | """
Tree_sort algorithm.
Build a Binary Search Tree and then iterate thru it to get a sorted list.
"""
from __future__ import annotations
from collections.abc import Iterator
from dataclasses import dataclass
@dataclass
class Node:
val: int
left: Node | None = None
right: Node | None = None
def __iter__(self) -> Iterator[int]:
if self.left:
yield from self.left
yield self.val
if self.right:
yield from self.right
def __len__(self) -> int:
return sum(1 for _ in self)
def insert(self, val: int) -> None:
if val < self.val:
if self.left is None:
self.left = Node(val)
else:
self.left.insert(val)
elif val > self.val:
if self.right is None:
self.right = Node(val)
else:
self.right.insert(val)
def tree_sort(arr: list[int]) -> tuple[int, ...]:
"""
>>> tree_sort([])
()
>>> tree_sort((1,))
(1,)
>>> tree_sort((1, 2))
(1, 2)
>>> tree_sort([5, 2, 7])
(2, 5, 7)
>>> tree_sort((5, -4, 9, 2, 7))
(-4, 2, 5, 7, 9)
>>> tree_sort([5, 6, 1, -1, 4, 37, 2, 7])
(-1, 1, 2, 4, 5, 6, 7, 37)
# >>> tree_sort(range(10, -10, -1)) == tuple(sorted(range(10, -10, -1)))
# True
"""
if len(arr) == 0:
return tuple(arr)
root = Node(arr[0])
for item in arr[1:]:
root.insert(item)
return tuple(root)
if __name__ == "__main__":
import doctest
doctest.testmod()
print(f"{tree_sort([5, 6, 1, -1, 4, 37, -3, 7]) = }")
| python | MIT | 2c15b8c54eb8130e83640fe1d911c10eb6cd70d4 | 2026-01-04T14:38:15.231112Z | false |
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