CODEWITHSUNDEEP
python
Sam
Sam

Reputation: 785

Converting a string into a list in Python

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']

Upvotes: 11

Views: 139822

Answers (7)

David Aniebo
David Aniebo

Reputation: 283

You can achieve this using the splitlines() method in python

data = """1000
2000
3000
4000"""

number_list = data.splitlines()

Upvotes: 3

Robert Goddard-Wright
Robert Goddard-Wright

Reputation: 105

If you already have a list that has been converted to a string by the str() method--like str(my_list)-- I have found that the easiest way to convert it back into a list is just to use eval(file_contents).

Upvotes: 0

Eli Bendersky
Eli Bendersky

Reputation: 273844

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

Upvotes: 24

rlotun
rlotun

Reputation: 8073

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

Upvotes: 1

dbr
dbr

Reputation: 169723

>>> 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']

Upvotes: 1

rytis
rytis

Reputation: 2721

    $ 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']
    >>>

Upvotes: 1

Nikola Smiljanić
Nikola Smiljanić

Reputation: 26863

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")]

Upvotes: 0

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