task_url stringlengths 30 116 | task_name stringlengths 2 86 | task_description stringlengths 0 14.4k | language_url stringlengths 2 53 | language_name stringlengths 1 52 | code stringlengths 0 61.9k |
|---|---|---|---|---|---|
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #Clean | Clean | square x = x * x
values :: {#Int}
values = {x \\ x <- [1 .. 10]} |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #Octave | Octave | function m = mode2(v)
sv = sort(v);
% build two vectors, vals and c, so that
% c(i) holds how many times vals(i) appears
i = 1; c = []; vals = [];
while (i <= numel(v) )
tc = sum(sv==sv(i)); % it would be faster to count
% them "by hand", since sv is sorted...
c = [c, tc];
... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #D | D | import std.stdio: writeln;
void main() {
// the associative array
auto aa = ["alice":2, "bob":97, "charlie":45];
// how to iterate key/value pairs:
foreach (key, value; aa)
writeln("1) Got key ", key, " with value ", value);
writeln();
// how to iterate the keys:
foreach (key, ... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Mathematica.2FWolfram_Language | Mathematica/Wolfram Language | b = {0.16666667, 0.5, 0.5, 0.16666667};
a = {1.00000000, -2.77555756*^-16, 3.33333333*^-01, -1.85037171*^-17};
signal = {-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412, -0.662370894973, -1.00700480494, -0.404707073677, 0.800482325044, 0.743500089861, 1.01090520172, 0.741527555207, 0.277841675195, 0.4008... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #MATLAB | MATLAB |
signal = [-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412, -0.662370894973, -1.00700480494, -0.404707073677 ,0.800482325044, 0.743500089861, 1.01090520172, 0.741527555207, 0.277841675195, 0.400833448236, -0.2085993586, -0.172842103641, -0.134316096293, 0.0259303398477, 0.490105989562, 0.549391221511, 0... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #Dyalect | Dyalect | func avg(args...) {
var acc = .0
var len = 0
for x in args {
len += 1
acc += x
}
acc / len
}
avg(1, 2, 3, 4, 5, 6) |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #E | E | def meanOrZero(numbers) {
var count := 0
var sum := 0
for x in numbers {
sum += x
count += 1
}
return sum / 1.max(count)
} |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Tcl | Tcl | set dict1 [dict create name "Rocket Skates" price 12.75 color yellow]
set dict2 [dict create price 15.25 color red year 1974]
dict for {key val} [dict merge $dict1 $dict2] {
puts "$key: $val"
} |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #VBA | VBA |
Private Type Associative
Key As String
Value As Variant
End Type
Sub Main_Array_Associative()
Dim BaseArray(2) As Associative, UpdateArray(2) As Associative
FillArrays BaseArray, UpdateArray
ReDim Result(UBound(BaseArray)) As Associative
MergeArray Result, BaseArray, UpdateArray
PrintOut Resul... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Ruby | Ruby | class Integer
def factorial
self == 0 ? 1 : (1..self).inject(:*)
end
end
def rand_until_rep(n)
rands = {}
loop do
r = rand(1..n)
return rands.size if rands[r]
rands[r] = true
end
end
runs = 1_000_000
puts " N average exp. diff ",
"=== ======== ======== ==========="... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Rust | Rust | extern crate rand;
use rand::{ThreadRng, thread_rng};
use rand::distributions::{IndependentSample, Range};
use std::collections::HashSet;
use std::env;
use std::process;
fn help() {
println!("usage: average_loop_length <max_N> <trials>");
}
fn main() {
let args: Vec<String> = env::args().collect();
le... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Smalltalk | Smalltalk | Object subclass: MovingAverage [
|valueCollection period collectedNumber sum|
MovingAverage class >> newWithPeriod: thePeriod [
|r|
r := super basicNew.
^ r initWithPeriod: thePeriod
]
initWithPeriod: thePeriod [
valueCollection := OrderedCollection new: thePeriod.
period := thePeriod.
collect... |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Lua | Lua | -- Returns true if x is prime, and false otherwise
function isPrime (x)
if x < 2 then return false end
if x < 4 then return true end
if x % 2 == 0 then return false end
for d = 3, math.sqrt(x), 2 do
if x % d == 0 then return false end
end
return true
end
-- Compute the prime factors of n
function fact... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #PHP | PHP |
<?php
function time2ang($tim) {
if (!is_string($tim)) return $tim;
$parts = explode(':',$tim);
if (count($parts)!=3) return $tim;
$sec = ($parts[0]*3600)+($parts[1]*60)+$parts[2];
$ang = 360.0 * ($sec/86400.0);
return $ang;
}
function ang2time($ang) {
if (!is_nu... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Scheme | Scheme | (cond-expand
(r7rs)
(chicken (import r7rs)))
(define-library (avl-trees)
;;
;; This library implements ‘persistent’ (that is, ‘immutable’) AVL
;; trees for R7RS Scheme.
;;
;; Included are generators of the key-data pairs in a tree. Because
;; the trees are persistent (‘immutable’), these generators ... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Phix | Phix | with javascript_semantics
function MeanAngle(sequence angles)
atom x = 0, y = 0
for i=1 to length(angles) do
atom ai_rad = angles[i]*PI/180
x += cos(ai_rad)
y += sin(ai_rad)
end for
if abs(x)<1e-16 then return "not meaningful" end if
return sprintf("%g",round(atan2(y,x)*180/P... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #FreeBASIC | FreeBASIC | ' FB 1.05.0 Win64
Sub quicksort(a() As Double, first As Integer, last As Integer)
Dim As Integer length = last - first + 1
If length < 2 Then Return
Dim pivot As Double = a(first + length\ 2)
Dim lft As Integer = first
Dim rgt As Integer = last
While lft <= rgt
While a(lft) < pivot
lft +=1
... |
http://rosettacode.org/wiki/Averages/Pythagorean_means | Averages/Pythagorean means | Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).
Show that
A
(
x
1
,
…
,
x
n
)
≥
G
(
x
1
,
…
,
x
n
)
≥
H
(
x
1
,
…
,
x
n
)
{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}
for this set of p... | #Kotlin | Kotlin | import kotlin.math.round
import kotlin.math.pow
fun Collection<Double>.geometricMean() =
if (isEmpty()) Double.NaN
else (reduce { n1, n2 -> n1 * n2 }).pow(1.0 / size)
fun Collection<Double>.harmonicMean() =
if (isEmpty() || contains(0.0)) Double.NaN
else size / fold(0.0) { n1, n2 -> n1 + 1.0 / n2 }
... |
http://rosettacode.org/wiki/Balanced_ternary | Balanced ternary | Balanced ternary is a way of representing numbers. Unlike the prevailing binary representation, a balanced ternary integer is in base 3, and each digit can have the values 1, 0, or −1.
Examples
Decimal 11 = 32 + 31 − 30, thus it can be written as "++−"
Decimal 6 = 32 − 31 + 0 × 30, thus it can be written as "+−0"
... | #REXX | REXX | /*REXX program converts decimal ◄───► balanced ternary; it also performs arithmetic. */
numeric digits 10000 /*be able to handle gihugic numbers. */
Ao = '+-0++0+' ; Abt = Ao /* [↓] 2 literals used by subroutine*/
Bo = '-436' ; Bbt = d2bt(Bo); ... |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Scala | Scala |
object BabbageProblem {
def main( args:Array[String] ): Unit = {
var x : Int = 524 // Sqrt of 269696 = 519.something
while( (x * x) % 1000000 != 269696 ){
if( x % 10 == 4 ) x = x + 2
else x = x + 8
}
println("The smallest positive integer whose ... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Raku | Raku | say 0.1 + 0.2 + 0.3 + 0.4 === 1.0000000000000000000000000000000000000000000000000000000000000000000000000; # True |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #ReScript | ReScript | let approx_eq = (v1, v2, epsilon) => {
abs_float (v1 -. v2) < epsilon
}
let test = (a, b) => {
let epsilon = 1e-18
Printf.printf("%g, %g => %b\n", a, b, approx_eq(a, b, epsilon))
}
{
test(100000000000000.01, 100000000000000.011)
test(100.01, 100.011)
test(10000000000000.001 /. 10000.0, 1000000000.000000... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #REXX | REXX | /*REXX program mimics an "approximately equal to" for comparing floating point numbers*/
numeric digits 15 /*what other FP hardware normally uses.*/
@.= /*assign default for the @ array. */
parse arg @.1 ... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #EchoLisp | EchoLisp |
(define (balance str)
(for/fold (closed 0) ((par str))
#:break (< closed 0 ) => closed
(+ closed
(cond
((string=? par "[") 1)
((string=? par "]") -1)
(else 0)))))
(define (task N)
(define str (list->string (append (make-list N "[") (make-list N "]"))))
(for ((i 10))
(set! str (list->string (shuffle (... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #Go | Go | package main
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
)
type pw struct {
account, password string
uid, gid uint
gecos
directory, shell string
}
type gecos struct {
fullname, office, extension, homephone, email string
}
func (p *pw) encode(w io.Writer) (int, e... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #AutoHotkey | AutoHotkey | associative_array := {key1: "value 1", "Key with spaces and non-alphanumeric characters !*+": 23}
MsgBox % associative_array.key1
. "`n" associative_array["Key with spaces and non-alphanumeric characters !*+"] |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Common_Lisp | Common Lisp | (defun factors (n &aux (lows '()) (highs '()))
(do ((limit (1+ (isqrt n))) (factor 1 (1+ factor)))
((= factor limit)
(when (= n (* limit limit))
(push limit highs))
(remove-duplicates (nreconc lows highs)))
(multiple-value-bind (quotient remainder) (floor n fa... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #Oz | Oz | declare
%%
%% INIT
%%
NBuckets = 100
StartVal = 50
ExpectedSum = NBuckets * StartVal
%% Makes a tuple and calls Fun for every field
fun {Make Label N Fun}
R = {Tuple.make Label N}
in
for I in 1..N do R.I = {Fun} end
R
end
Buckets = {Make buckets NBuckets fun {$} {Cell.new StartV... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Liberty_BASIC | Liberty BASIC |
a=42
call assert a=42
print "passed"
a=41
call assert a=42
print "failed (we never get here)"
end
sub assert cond
if cond=0 then 'simulate error, mentioning "AssertionFailed"
AssertionFailed(-1)=0
end if
end sub
|
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Lingo | Lingo | -- in a movie script
on assert (ok, message)
if not ok then
if not voidP(message) then _player.alert(message)
abort -- exits from current call stack, i.e. also from the caller function
end if
end
-- anywhere in the code
on test
x = 42
assert(x=42, "Assertion 'x=42' failed")
put "this shows up"
x =... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Lisaac | Lisaac | ? { n = 42 }; |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #Clio | Clio | [1 2 3 4] * 2 + 1 -> print |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #Clojure | Clojure | ;; apply a named function, inc
(map inc [1 2 3 4]) |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #ooRexx | ooRexx |
-- will work with just about any collection...
call testMode .array~of(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
call testMode .list~of(10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, .11)
call testMode .queue~of(30, 10, 20, 30, 40, 50, -100, 4.7, -11e2)
::routine testMode
use arg list
say "list =" list~makearray~toString("l",... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #Dao | Dao |
dict = { 'def' => 1, 'abc' => 2 }
for( keyvalue in dict ) io.writeln( keyvalue );
for( key in dict.keys(); value in dict.values() ) io.writeln( key, value )
dict.iterate { [key, value]
io.writeln( key, value )
}
|
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #Dart | Dart |
main(){
var fruits = {
'apples': 'red',
'oranges': 'orange',
'bananas': 'yellow',
'pears': 'green',
'plums': 'purple'
};
print('Key Value pairs:');
fruits.forEach( (fruits, color) => print( '$fruits are $color' ) );
print('\nKeys only:');
fruits.keys.forEach( ( key ) => print( key ) );
pri... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Nim | Nim |
import strformat
func filter(a, b, signal: openArray[float]): seq[float] =
result.setLen(signal.len)
for i in 0..signal.high:
var tmp = 0.0
for j in 0..min(i, b.high):
tmp += b[j] * signal[i - j]
for j in 1..min(i, a.high):
tmp -= a[j] * result[i - j]
tmp /= a[0]
result[i] = ... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Objeck | Objeck | class DigitalFilter {
function : Main(args : String[]) ~ Nil {
a := [1.00000000, -2.77555756e-16, 3.33333333e-01, -1.85037171e-17];
b := [0.16666667, 0.5, 0.5, 0.16666667];
signal := [-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412,
-0.662370894973, -1.00700480494, -0.404707073677, 0.... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #EasyLang | EasyLang | func mean . f[] r .
for i range len f[]
s += f[i]
.
r = s / len f[]
.
f[] = [ 1 2 3 4 5 6 7 8 ]
call mean f[] r
print r |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #EchoLisp | EchoLisp |
(lib 'math)
(mean '(1 2 3 4)) ;; mean of a list
→ 2.5
(mean #(1 2 3 4)) ;; mean of a vector
→ 2.5
(lib 'sequences)
(mean [1 3 .. 10]) ;; mean of a sequence
→ 5
;; error handling
(mean 'elvis)
⛔ error: mean : expected sequence : elvis
(mean ())
💣 error: mean : null is not an object
(mean #())
... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Wren | Wren | var mergeMaps = Fn.new { |m1, m2|
var m3 = {}
for (key in m1.keys) m3[key] = m1[key]
for (key in m2.keys) m3[key] = m2[key]
return m3
}
var base = { "name": "Rocket Skates" , "price": 12.75, "color": "yellow" }
var update = { "price": 15.25, "color": "red", "year": 1974 }
var merged = mergeMaps.c... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Vlang | Vlang | type Generic = int|string|f64
type Assoc = map[string]Generic
fn merge(base Assoc, update Assoc) Assoc {
mut result := Assoc(map[string]Generic{})
for k, v in base {
result[k] = v
}
for k, v in update {
result[k] = v
}
return result
}
fn main() {
base := Assoc({"name": Ge... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Wren_2 | Wren | var mergeMaps = Fn.new { |m1, m2|
var m3 = {}
for (key in m1.keys) m3[key] = m1[key]
for (key in m2.keys) m3[key] = m2[key]
return m3
}
var base = { "name": "Rocket Skates" , "price": 12.75, "color": "yellow" }
var update = { "price": 15.25, "color": "red", "year": 1974 }
var merged = mergeMaps.c... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Scala | Scala |
import scala.util.Random
object AverageLoopLength extends App {
val factorial: LazyList[Double] = 1 #:: factorial.zip(LazyList.from(1)).map(n => n._2 * factorial(n._2 - 1))
val results = for (n <- 1 to 20;
avg = tested(n, 1000000);
theory = expected(n)
... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Swift | Swift | struct SimpleMovingAverage {
var period: Int
var numbers = [Double]()
mutating func addNumber(_ n: Double) -> Double {
numbers.append(n)
if numbers.count > period {
numbers.removeFirst()
}
guard !numbers.isEmpty else {
return 0
}
return numbers.reduce(0, +) / Double(num... |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Maple | Maple | attractivenumbers := proc(n::posint)
local an, i;
an :=[]:
for i from 1 to n do
if isprime(NumberTheory:-NumberOfPrimeFactors(i)) then
an := [op(an), i]:
end if:
end do:
end proc:
attractivenumbers(120); |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | ClearAll[AttractiveNumberQ]
AttractiveNumberQ[n_Integer] := FactorInteger[n][[All, 2]] // Total // PrimeQ
Reap[Do[If[AttractiveNumberQ[i], Sow[i]], {i, 120}]][[2, 1]] |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #PicoLisp | PicoLisp | (load "@lib/math.l")
(de meanTime (Lst)
(let Tim
(*/
(atan2
(sum '((S) (sin (*/ ($tim S) pi 43200))) Lst)
(sum '((S) (cos (*/ ($tim S) pi 43200))) Lst) )
43200 pi )
(tim$ (% (+ Tim 86400) 86400) T) ) ) |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #PL.2FI | PL/I | *process source attributes xref;
avt: Proc options(main);
/*--------------------------------------------------------------------
* 25.06.2014 Walter Pachl taken from REXX
*-------------------------------------------------------------------*/
Dcl (addr,hbound,sin,cos,atan) Builtin;
Dcl sysprint Print;
Dcl times(4... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Sidef | Sidef | class AVLtree {
has root = nil
struct Node {
Number key,
Number balance = 0,
Node left = nil,
Node right = nil,
Node parent = nil,
}
method insert(key) {
if (root == nil) {
root = Node(key)
return true
}
var ... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #PHP | PHP | <?php
$samples = array(
'1st' => array(350, 10),
'2nd' => array(90, 180, 270, 360),
'3rd' => array(10, 20, 30)
);
foreach($samples as $key => $sample){
echo 'Mean angle for ' . $key . ' sample: ' . meanAngle($sample) . ' degrees.' . PHP_EOL;
}
function meanAngle ($angles){
$y_part = $x_part = 0;
$size = cou... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #GAP | GAP | Median := function(v)
local n, w;
w := SortedList(v);
n := Length(v);
return (w[QuoInt(n + 1, 2)] + w[QuoInt(n, 2) + 1]) / 2;
end;
a := [41, 56, 72, 17, 93, 44, 32];
b := [41, 72, 17, 93, 44, 32];
Median(a);
# 44
Median(b);
# 85/2 |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #Go | Go | package main
import (
"fmt"
"sort"
)
func main() {
fmt.Println(median([]float64{3, 1, 4, 1})) // prints 2
fmt.Println(median([]float64{3, 1, 4, 1, 5})) // prints 3
}
func median(a []float64) float64 {
sort.Float64s(a)
half := len(a) / 2
m := a[half]
if len(a)%2 == 0 {
m ... |
http://rosettacode.org/wiki/Averages/Pythagorean_means | Averages/Pythagorean means | Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).
Show that
A
(
x
1
,
…
,
x
n
)
≥
G
(
x
1
,
…
,
x
n
)
≥
H
(
x
1
,
…
,
x
n
)
{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}
for this set of p... | #Lasso | Lasso | define arithmetic_mean(a::staticarray)::decimal => {
//sum of the list divided by its length
return (with e in #a sum #e) / decimal(#a->size)
}
define geometric_mean(a::staticarray)::decimal => {
// The geometric mean is the nth root of the product of the list
local(prod = 1)
with e in #a do => { #prod *= #e }
re... |
http://rosettacode.org/wiki/Balanced_ternary | Balanced ternary | Balanced ternary is a way of representing numbers. Unlike the prevailing binary representation, a balanced ternary integer is in base 3, and each digit can have the values 1, 0, or −1.
Examples
Decimal 11 = 32 + 31 − 30, thus it can be written as "++−"
Decimal 6 = 32 − 31 + 0 × 30, thus it can be written as "+−0"
... | #Ruby | Ruby | class BalancedTernary
include Comparable
def initialize(str = "")
if str =~ /[^-+0]+/
raise ArgumentError, "invalid BalancedTernary number: #{str}"
end
@digits = trim0(str)
end
I2BT = {0 => ["0",0], 1 => ["+",0], 2 => ["-",1]}
def self.from_int(value)
n = value.to_i
digits = ""
... |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Scheme | Scheme |
(define (digits n)
(string->list (number->string n)))
(define (ends-with list tail)
;; does list end with tail?
(starts-with (reverse list)
(reverse tail)))
(define (starts-with list head)
(cond ((null? head)
#t)
((null? list)
#f)
((equal? (car list) (car h... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Ruby | Ruby | require "bigdecimal"
testvalues = [[100000000000000.01, 100000000000000.011],
[100.01, 100.011],
[10000000000000.001 / 10000.0, 1000000000.0000001000],
[0.001, 0.0010000001],
[0.000000000000000000000101, 0... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Rust | Rust | /// Return whether the two numbers `a` and `b` are close.
/// Closeness is determined by the `epsilon` parameter -
/// the numbers are considered close if the difference between them
/// is no more than epsilon * max(abs(a), abs(b)).
fn isclose(a: f64, b: f64, epsilon: f64) -> bool {
(a - b).abs() <= a.abs().max(b... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #Elena | Elena | import system'routines;
import extensions;
import extensions'text;
randomBrackets(len)
{
if (0 == len)
{
^emptyString
}
else
{
var brackets :=
Array.allocate(len).populate:(i => $91)
+
Array.allocate(len).populate:(i => $93);
brack... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #Groovy | Groovy | class PasswdRecord {
String account, password, directory, shell
int uid, gid
SourceRecord source
private static final fs = ':'
private static final fieldNames = ['account', 'password', 'uid', 'gid', 'source', 'directory', 'shell']
private static final stringFields = ['account', 'password', 'di... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #AutoIt | AutoIt | ; Associative arrays in AutoIt.
; All the required functions are below the examples.
; Initialize an error handler to deal with any COM errors..
global $oMyError = ObjEvent("AutoIt.Error", "AAError")
; first example, simple.
global $simple
; Initialize your array ...
AAInit($simple)
AAAdd($simple, "Appple", "fr... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Cowgol | Cowgol | include "cowgol.coh";
const AMOUNT := 20;
sub countFactors(n: uint16): (count: uint16) is
var i: uint16 := 1;
count := 1;
while i <= n/2 loop
if n%i == 0 then
count := count + 1;
end if;
i := i + 1;
end loop;
end sub;
var max: uint16 := 0;
var seen: uint8 := 0;
va... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Crystal | Crystal | def count_divisors(n : Int64) : Int64
return 1_i64 if n < 2
count = 2_i64
i = 2
while i <= n // 2
count += 1 if n % i == 0
i += 1
end
count
end
max_div = 0_i64
count = 0_i64
print "The first 20 anti-primes are: "
n = 1_i64
while count < 20
d = count_divisors n
if d > max_div
prin... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #PARI.2FGP | PARI/GP | use strict;
use 5.10.0;
use threads 'yield';
use threads::shared;
my @a :shared = (100) x 10;
my $stop :shared = 0;
sub pick2 {
my $i = int(rand(10));
my $j;
$j = int(rand(10)) until $j != $i;
($i, $j)
}
sub even {
lock @a;
my ($i, $j) = pick2;
my $sum = $a[$i] + $a[$j];
$a[$i] = int($sum / 2);
$a[$j] ... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Lua | Lua | a = 5
assert (a == 42)
assert (a == 42,'\''..a..'\' is not the answer to life, the universe, and everything') |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #M2000_Interpreter | M2000 Interpreter |
Module Assert {
\\ This is a global object named Rec
Global Group Rec {
Private:
document doc$="Error List at "+date$(today)+" "+time$(now)+{
}
Public:
lastfilename$="noname.err"
Module Error(a$) {
if a$="" then exit
... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Maple | Maple | a := 5:
ASSERT( a = 42 );
ASSERT( a = 42, "a is not the answer to life, the universe, and everything" ); |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #CLU | CLU | % This procedure will call a given procedure with each element
% of the given array. Thanks to CLU's type parameterization,
% it will work for any type of element.
apply_to_all = proc [T: type] (a: array[T], f: proctype(int,T))
for i: int in array[T]$indexes(a) do
f(i, a[i])
end
end apply_to_all
% Cal... |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #COBOL | COBOL | IDENTIFICATION DIVISION.
PROGRAM-ID. Map.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 Table-Size CONSTANT 30.
LOCAL-STORAGE SECTION.
01 I USAGE UNSIGNED-INT.
LINKAGE SECTION.
01 Table-Param.
03 Table-Values USAGE COMP-2 OCCURS Table-Size... |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #Oz | Oz | declare
fun {Mode Xs}
Freq = {Dictionary.new}
for X in Xs do
Freq.X := {CondSelect Freq X 0} + 1
end
MaxCount = {FoldL {Dictionary.items Freq} Max 0}
in
for Value#Count in {Dictionary.entries Freq} collect:C do
if Count == MaxCount then
{C Value}
end
end
e... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #Delphi | Delphi | program AssociativeArrayIteration;
{$APPTYPE CONSOLE}
uses SysUtils, Generics.Collections;
var
i: Integer;
s: string;
lDictionary: TDictionary<string, Integer>;
lPair: TPair<string, Integer>;
begin
lDictionary := TDictionary<string, Integer>.Create;
try
lDictionary.Add('foo', 5);
lDictionary.A... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #ooRexx | ooRexx | /* REXX */
a=.array~of(1.00000000, -2.77555756e-16, 3.33333333e-01, -1.85037171e-17)
b=.array~of(0.16666667, 0.5, 0.5, 0.16666667)
s=.array~of(-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412,,
-0.662370894973, -1.00700480494, -0.404707073677 ,0.800482325044,,
0.743500089861, 1.01... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Perl | Perl | use strict;
use List::AllUtils 'natatime';
sub TDF_II_filter {
our(@signal,@a,@b);
local(*signal,*a,*b) = (shift, shift, shift);
my @out = (0) x $#signal;
for my $i (0..@signal-1) {
my $this;
map { $this += $b[$_] * $signal[$i-$_] if $i-$_ >= 0 } 0..@b;
map { $this -= $a[$_... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #ECL | ECL |
AveVal(SET OF INTEGER s) := AVE(s);
//example usage
SetVals := [14,9,16,20,91];
AveVal(SetVals) //returns 30.0 ;
|
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #Elena | Elena | import extensions;
extension op
{
average()
{
real sum := 0;
int count := 0;
var enumerator := self.enumerator();
while (enumerator.next())
{
sum += enumerator.get();
count += 1;
};
^ sum / count
}
}
public program()
{... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #zkl | zkl | base:=Dictionary(
"name", "Rocket Skates",
"price", 12.75,
"color", "yellow",);
update:=Dictionary(
"price", 15.25,
"color", "red",
"year", 1974,);
update.pump( new:=base.copy() );
new.pump(Void,fcn([(k,v)]){ println("%s\t%s".fmt(k,v)) }); |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Scheme | Scheme |
(import (scheme base)
(scheme write)
(srfi 1 lists)
(only (srfi 13 strings) string-pad-right)
(srfi 27 random-bits))
(define (analytical-function n)
(define (factorial n)
(fold * 1 (iota n 1)))
;
(fold (lambda (i sum)
(+ sum
(/ (factorial n) (expt n ... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Tcl | Tcl | oo::class create SimpleMovingAverage {
variable vals idx
constructor {{period 3}} {
set idx end-[expr {$period-1}]
set vals {}
}
method val x {
set vals [lrange [list {*}$vals $x] $idx end]
expr {[tcl::mathop::+ {*}$vals]/double([llength $vals])}
}
} |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Modula-2 | Modula-2 | MODULE AttractiveNumbers;
FROM InOut IMPORT WriteCard, WriteLn;
CONST
Max = 120;
VAR
n, col: CARDINAL;
Prime: ARRAY [1..Max] OF BOOLEAN;
PROCEDURE Sieve;
VAR i, j: CARDINAL;
BEGIN
Prime[1] := FALSE;
FOR i := 2 TO Max DO
Prime[i] := TRUE;
END;
FOR i := 2 TO Max DIV 2 DO
... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #PowerShell | PowerShell |
function Get-MeanTimeOfDay
{
[CmdletBinding()]
[OutputType([timespan])]
Param
(
[Parameter(Mandatory=$true,
ValueFromPipeline=$true,
ValueFromPipelineByPropertyName=$true)]
[ValidatePattern("(?:2[0-3]|[01]?[0-9])[:.][0-5]?[0-9][:.][0-5]?[0-9]")]
... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Simula | Simula | CLASS AVL;
BEGIN
! AVL TREE ADAPTED FROM JULIENNE WALKER'S PRESENTATION AT ;
! HTTP://ETERNALLYCONFUZZLED.COM/TUTS/DATASTRUCTURES/JSW_TUT_AVL.ASPX. ;
! THIS PORT USES SIMILAR INDENTIFIER NAMES. ;
! THE KEY INTERFACE MUST BE SUPPORTED BY DATA STORED IN THE AVL TREE. ;
CLASS KEY;
VIRTUAL:
... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #PicoLisp | PicoLisp | (load "@lib/math.l")
(de meanAngle (Lst)
(*/
(atan2
(sum '((A) (sin (*/ A pi 180.0))) Lst)
(sum '((A) (cos (*/ A pi 180.0))) Lst) )
180.0 pi ) )
(for L '((350.0 10.0) (90.0 180.0 270.0 360.0) (10.0 20.0 30.0))
(prinl
"The mean angle of ["
(glue ", " (mapcar round L '(... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #PL.2FI | PL/I | averages: procedure options (main); /* 31 August 2012 */
declare b1(2) fixed initial (350, 10);
declare b2(4) fixed initial (90, 180, 270, 360);
declare b3(3) fixed initial (10, 20, 30);
put edit ( b1) (f(7));
put edit ( ' mean=', mean(b1) ) (a, f(7) );
put skip edit ( b3) (f(7));
p... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #PowerShell | PowerShell |
function Get-MeanAngle ([double[]]$Angles)
{
$x = ($Angles | ForEach-Object {[Math]::Cos($_ * [Math]::PI / 180)} | Measure-Object -Average).Average
$y = ($Angles | ForEach-Object {[Math]::Sin($_ * [Math]::PI / 180)} | Measure-Object -Average).Average
[Math]::Atan2($y, $x) * 180 / [Math]::PI
}
|
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #Groovy | Groovy | def median(Iterable col) {
def s = col as SortedSet
if (s == null) return null
if (s.empty) return 0
def n = s.size()
def m = n.intdiv(2)
def l = s.collect { it }
n%2 == 1 ? l[m] : (l[m] + l[m-1])/2
} |
http://rosettacode.org/wiki/Averages/Pythagorean_means | Averages/Pythagorean means | Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).
Show that
A
(
x
1
,
…
,
x
n
)
≥
G
(
x
1
,
…
,
x
n
)
≥
H
(
x
1
,
…
,
x
n
)
{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}
for this set of p... | #Liberty_BASIC | Liberty BASIC | for i = 1 to 10
a = a + i
next
ArithmeticMean = a/10
b = 1
for i = 1 to 10
b = b * i
next
GeometricMean = b ^ (1/10)
for i = 1 to 10
c = c + (1/i)
next
HarmonicMean = 10/c
print "ArithmeticMean: ";ArithmeticMean
print "Geometric Mean: ";GeometricMean
print "Harmonic Mean: ";HarmonicMean
if (Arithmet... |
http://rosettacode.org/wiki/Balanced_ternary | Balanced ternary | Balanced ternary is a way of representing numbers. Unlike the prevailing binary representation, a balanced ternary integer is in base 3, and each digit can have the values 1, 0, or −1.
Examples
Decimal 11 = 32 + 31 − 30, thus it can be written as "++−"
Decimal 6 = 32 − 31 + 0 × 30, thus it can be written as "+−0"
... | #Rust | Rust | use std::{
cmp::min,
convert::{TryFrom, TryInto},
fmt,
ops::{Add, Mul, Neg},
str::FromStr,
};
fn main() -> Result<(), &'static str> {
let a = BalancedTernary::from_str("+-0++0+")?;
let b = BalancedTernary::from(-436);
let c = BalancedTernary::from_str("+-++-")?;
println!("a = {} = ... |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Scilab | Scilab | n=2;
flag=%F
while ~flag
n = n+2;
if pmodulo(n*n,1000000)==269696 then
flag=%T;
end
end
disp(n); |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Seed7 | Seed7 | $ include "seed7_05.s7i";
const proc: main is func
local
var integer: current is 0;
begin
while current ** 2 rem 1000000 <> 269696 do
incr(current);
end while;
writeln("The square of " <& current <& " is " <& current ** 2);
end func; |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Scala | Scala | object Approximate extends App {
val (ok, notOk, ε) = ("👌", "❌", 1e-18d)
private def approxEquals(value: Double, other: Double, epsilon: Double) =
scala.math.abs(value - other) < epsilon
private def test(a: BigDecimal, b: BigDecimal, expected: Boolean): Unit = {
val result = approxEquals(a.toDouble, ... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Sidef | Sidef | [
100000000000000.01, 100000000000000.011,
100.01, 100.011,
10000000000000.001 / 10000.0, 1000000000.0000001000,
0.001, 0.0010000001,
0.000000000000000000000101, 0.0,
sqrt(2) * sqrt(2), 2.0,
-sqrt(2) * sqrt(2), -2.0,
sqrt(-2) * sqrt(-2), -2.0,
cbrt(3)**3, 3,
cbrt(-3)**3, -3,
... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #Elixir | Elixir | defmodule Balanced_brackets do
def task do
Enum.each(0..5, fn n ->
brackets = generate(n)
result = is_balanced(brackets) |> task_balanced
IO.puts "#{brackets} is #{result}"
end)
end
defp generate( 0 ), do: []
defp generate( n ) do
for _ <- 1..2*n, do: Enum.random ["[", "]"]
end... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #Haskell | Haskell |
{-# LANGUAGE RecordWildCards #-}
import System.IO
import Data.List (intercalate)
data Gecos = Gecos { fullname :: String
, office :: String
, extension :: String
, homephone :: String
, email :: String
}
dat... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #AWK | AWK | BEGIN {
a["red"] = 0xff0000
a["green"] = 0x00ff00
a["blue"] = 0x0000ff
for (i in a) {
printf "%8s %06x\n", i, a[i]
}
# deleting a key/value
delete a["red"]
for (i in a) {
print i
}
# check if a key exists
print ( "red" in a ) # print 0
print ( "blue" in a ) # print 1
} |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #D | D | import std.stdio;
int countDivisors(int n) {
if (n < 2) {
return 1;
}
int count = 2; // 1 and n
for (int i = 2; i <= n/2; ++i) {
if (n % i == 0) {
++count;
}
}
return count;
}
void main() {
int maxDiv, count;
writeln("The first 20 anti-primes are:"... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Delphi | Delphi | defmodule AntiPrimes do
def divcount(n) when is_integer(n), do: divcount(n, 1, 0)
def divcount(n, d, count) when d * d > n, do: count
def divcount(n, d, count) do
divs = case rem(n, d) do
0 ->
case n - d * d do
0 -> 1
_ -> 2
end
_ -> 0
end
divcount(n, d + 1, count + divs)
end
def ... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #Perl | Perl | use strict;
use 5.10.0;
use threads 'yield';
use threads::shared;
my @a :shared = (100) x 10;
my $stop :shared = 0;
sub pick2 {
my $i = int(rand(10));
my $j;
$j = int(rand(10)) until $j != $i;
($i, $j)
}
sub even {
lock @a;
my ($i, $j) = pick2;
my $sum = $a[$i] + $a[$j];
$a[$i] = int($sum / 2);
$a[$j] ... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | Assert[var===42] |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #MATLAB_.2F_Octave | MATLAB / Octave | assert(x == 42,'x = %d, not 42.',x); |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Metafont | Metafont | def assert(expr t) = if not (t): errmessage("assertion failed") fi enddef; |
Subsets and Splits
Rosetta Code COBOL Python Hard Tasks
Identifies and retrieves challenging tasks that exist in both COBOL and Python, revealing cross-language programming patterns and difficulty levels for comparative analysis.
Rosetta Code Task Comparisons
Identifies tasks common to both COBOL and Python languages that are described as having difficulty levels, revealing cross-language task similarities and providing useful comparative programming examples.
Select Specific Languages Codes
Retrieves specific programming language names and codes from training data, providing basic filtering but limited analytical value beyond identifying these particular languages.