How do you read a file into a list in Python? [duplicate]

Answer 1

f = open("file.txt")
lines = f.readlines()

Look over here. readlines() returns a list containing one line per element. Note that these lines contain the \n (newline-character) at the end of the line. You can strip off this newline-character by using the strip()-method. I.e. call lines[index].strip() in order to get the string without the newline character.

As joaquin noted, do not forget to f.close() the file.

Converting strint to integers is easy: int("12").

Answer 2

To summarize a bit from what people have been saying:

f=open('data.txt', 'w') # will make a new file or erase a file of that name if it is present
f=open('data.txt', 'r') # will open a file as read-only
f=open('data.txt', 'a') # will open a file for appending (appended data goes to the end of the file)

If you wish have something in place similar to a try/catch

with open('data.txt') as f:
    for line in f:
        print line

I think @movieyoda code is probably what you should use however

Answer 3

If you have multiple numbers per line and you have multiple lines, you can read them in like this:

    #!/usr/bin/env python

    from os.path import dirname

    with open(dirname(__file__) + '/data/path/filename.txt') as input_data:
        input_list= [map(int,num.split()) for num in input_data.readlines()]

Answer 4

You need to pass a filename string to open. There's an extra complication when the string has \ in it, because that's a special string escape character to Python. You can fix this by doubling up each as \\ or by putting a r in front of the string as follows: r'C:\name\MyDocuments\numbers'.

Edit: The edits to the question make it completely different from the original, and since none of them was from the original poster I'm not sure they're warrented. However it does point out one obvious thing that might have been overlooked, and that's how to add "My Documents" to a filename.

In an English version of Windows XP, My Documents is actually C:\Documents and Settings\name\My Documents. This means the open call should look like:

open(r"C:\Documents and Settings\name\My Documents\numbers", 'r')

I presume you're using XP because you call it My Documents - it changed in Vista and Windows 7. I don't know if there's an easy way to look this up automatically in Python.

Answer 5

hdl = open("C:/name/MyDocuments/numbers", 'r')
milist = hdl.readlines()
hdl.close()

Answer 6

with open('C:/path/numbers.txt') as f:
    lines = f.read().splitlines()

this will give you a list of values (strings) you had in your file, with newlines stripped.

also, watch your backslashes in windows path names, as those are also escape chars in strings. You can use forward slashes or double backslashes instead.