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 开发者_开发百科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']
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
$ 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']
>>>
>>> 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']
with open('file.txt', 'rb') as f:
data = f.read()
lines = [s.strip() for s in data.split('\n') if s]
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")]
精彩评论