Converting a string into a list in Python

Question

I have a text document that contains a list of numbers and I want to convert it to a list. Right now I can only get the entire list in the 0th entry of the list, but I want each number to be an element of a list. Does anyone know of an easy way to do this in Python?

1000
2000
3000
4000

to

['1000','2000','3000','4000']

Answer 1

>>> open("myfile.txt").readlines()
>>> lines = open("myfile.txt").readlines()
>>> lines
['1000\n', '2000\n', '3000\n', '4000\n']
>>> clean_lines = [x.strip() for x in lines]
>>> clean_lines
['1000', '2000', '3000', '4000']

Or, if you have a string already, use str.split:

>>> myfile
'1000\n2000\n3000\n4000\n'
>>> myfile.splitlines()
['1000', '2000', '3000', '4000', '']

You can remove the empty element with a list comprehension (or just a regular for loop)

>>> [x for x in myfile.splitlines() if x != ""]
['1000', '2000', '3000', '4000']

Answer 2

To convert a Python string into a list use the str.split method:

>>> '1000 2000 3000 4000'.split()
['1000', '2000', '3000', '4000']

split has some options: look them up for advanced uses.

You can also read the file into a list with the readlines() method of a file object - it returns a list of lines. For example, to get a list of integers from that file, you can do:

lst = map(int, open('filename.txt').readlines())

---

P.S: See some other methods for doing the same in the comments. Some of those methods are nicer (more Pythonic) than mine

Answer 3

You might need to strip newlines.

# list of strings
[number for number in open("file.txt")]

# list of integers
[int(number) for number in open("file.txt")]

Answer 4

    $ cat > t.txt
    1
    2
    3
    4
    ^D
    $ python
    Python 2.6.1 (r261:67515, Jul  7 2009, 23:51:51) 
    [GCC 4.2.1 (Apple Inc. build 5646)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> l = [l.strip() for l in open('t.txt')]
    >>> l
    ['1', '2', '3', '4']
    >>> 

Answer 5

   with open('file.txt', 'rb') as f:
       data = f.read()
   lines = [s.strip() for s in data.split('\n') if s]