text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
|---|---|---|
necessarily a big deal but sometimes it | 842.82 | 3.36 |
can create problems files could get | 844.62 | 3.48 |
corrupted or accidentally deleted or the | 846.18 | 3.3 |
liked depending on what happens in your | 848.1 | 3.12 |
code so it turns out that you don't | 849.48 | 4.56 |
strictly need to call close on the file | 851.22 | 4.679 |
yourself if you take another approach | 854.04 | 5.7 |
instead more pythonic when manipulating | 855.899 | 7.081 |
files is to do this to introduce this | 859.74 | 6.06 |
other keyword called quite simply with | 862.98 | 5.52 |
that allows you to specify that in this | 865.8 | 5.039 |
context I want you to open and | 868.5 | 5.1 |
automatically close some file so how do | 870.839 | 4.921 |
we use with it simply looks like this | 873.6 | 4.14 |
let me go back to my code here I've | 875.76 | 4.199 |
gotten rid of the close line and I'm now | 877.74 | 4.14 |
just going to say this instead instead | 879.959 | 4.56 |
of saying file equals open I'm going to | 881.88 | 6 |
say with open then the same arguments as | 884.519 | 5.521 |
before and somewhat curiously I'm going | 887.88 | 3.84 |
to put the variable at the end of the | 890.04 | 3.72 |
line why that's just the way this is | 891.72 | 4.44 |
done you say with you call the function | 893.76 | 4.74 |
in question and then you say as and | 896.16 | 4.02 |
specify the name of the variable that | 898.5 | 3.54 |
should be assigned find the return value | 900.18 | 3.959 |
of open then I'm going to go ahead and | 902.04 | 4.5 |
indent the line underneath so that the | 904.139 | 4.44 |
line of code that's writing the name is | 906.54 | 4.2 |
now in the context of this with | 908.579 | 4.32 |
statement which just ensures that | 910.74 | 4.5 |
automatically if I had more code in this | 912.899 | 5.221 |
file down below no longer indented the | 915.24 | 4.98 |
file would be automatically closed as | 918.12 | 4.44 |
soon as line 4 is done executing so it | 920.22 | 3.72 |
doesn't change what has just happened | 922.56 | 3.18 |
but it does automate the process of at | 923.94 | 3.48 |
least closing things for us just to | 925.74 | 3 |
ensure I don't forget and so that | 927.42 | 4.08 |
something doesn't go wrong | 928.74 | 5.58 |
but suppose now that I wanted to read | 931.5 | 4.8 |
these names from the file all I've done | 934.32 | 3.6 |
thus far is write code that writes names | 936.3 | 3.659 |
to the file but let's assume now that we | 937.92 | 3.96 |
have all of these names in the file and | 939.959 | 4.081 |
heck let's go ahead and add one more let | 941.88 | 3.78 |
me go ahead and run this one more time | 944.04 | 4.32 |
python of names.pi and let's add in | 945.66 | 5.099 |
Draco to the mix so now that we have all | 948.36 | 4.56 |
four of these names here how might we | 950.759 | 4.5 |
want to read them back well let me | 952.92 | 4.56 |
propose that we go into names.pi now or | 955.259 | 3.181 |
we could create another program | 957.48 | 2.76 |
altogether but I'm going to keep reusing | 958.44 | 3.72 |
the same name just to keep us focused on | 960.24 | 3.779 |
this and now I'm going to write code | 962.16 | 4.919 |
that reads an existing file with | 964.019 | 6.18 |
Hermione Harry Ron and Draco together | 967.079 | 5.341 |
and how do I do this well it's similar | 970.199 | 3.961 |
in spirit I'm going to start this time | 972.42 | 4.44 |
with with open and then the first | 974.16 | 3.9 |
argument is going to be the name of the | 976.86 | 3.599 |
file that I want to open as before and | 978.06 | 4.26 |
I'm going to open it this time in read | 980.459 | 4.201 |
mode quote unquote R and to read a file | 982.32 | 5.519 |
just means to load it not to save it and | 984.66 | 5.64 |
I'm going to name the return value file | 987.839 | 4.141 |
and now I'm going to do this yes and | 990.3 | 3 |
there's a number of ways I can do this | 991.98 | 3.24 |
but one way to read all of the lines | 993.3 | 4.14 |
from the file at once would be this let | 995.22 | 4.44 |
me declare a variable called lines let | 997.44 | 4.44 |
me access that file and call a function | 999.66 | 4.02 |
or a method that comes with it called | 1,001.88 | 3.66 |
read lines so if you read the | 1,003.68 | 4.079 |
documentation on file i o and python | 1,005.54 | 4.5 |
you'll see that open files come with a | 1,007.759 | 4.2 |
special method whose purpose in life is | 1,010.04 | 4.38 |
to read all the lines from the file and | 1,011.959 | 5.221 |
return them to me as a list so what this | 1,014.42 | 4.8 |
line 2 is doing is it's reading all of | 1,017.18 | 4.32 |
the lines from that file storing them in | 1,019.22 | 5.099 |
a variable called lines now suppose I | 1,021.5 | 4.319 |
want to iterate over all of those lines | 1,024.319 | 4.02 |
and print out each of those names for | 1,025.819 | 4.921 |
line in lines this is just a standard | 1,028.339 | 6.061 |
for Loop in Python lines as a list line | 1,030.74 | 4.92 |
is the variable that will be | 1,034.4 | 3.059 |
automatically be set to each of those | 1,035.66 | 3.539 |
lines let me go ahead and print out | 1,037.459 | 3.96 |
something like oh hello | 1,039.199 | 5.1 |
uh comma and then I'll print out the | 1,041.419 | 4.201 |
line itself | 1,044.299 | 3.301 |
all right so let me go to my terminal | 1,045.62 | 5.64 |
window run python of names.pi now I have | 1,047.6 | 5.939 |
not deleted names.txt so it still | 1,051.26 | 3.96 |
contains all four of those names and hit | 1,053.539 | 5.701 |
enter and okay it's not bad but it's a | 1,055.22 | 6 |
little ugly here | 1,059.24 | 4.799 |
what's going on when I ran names.pi it's | 1,061.22 | 4.74 |
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