Split by comma and strip whitespace in Python

I have some python code that splits on comma, but doesn't strip the whitespace:

>>> string = "blah, lots , of , spaces, here " >>> mylist = string.split(',') >>> print mylist ['blah', ' lots ', ' of ', ' spaces', ' here '] 

I would rather end up with whitespace removed like this:

['blah', 'lots', 'of', 'spaces', 'here'] 

I am aware that I could loop through the list and strip() each item but, as this is Python, I'm guessing there's a quicker, easier and more elegant way of doing it.

11 Answers

Use list comprehension -- simpler, and just as easy to read as a for loop.

my_string = "blah, lots , of , spaces, here " result = [x.strip() for x in my_string.split(',')] # result is ["blah", "lots", "of", "spaces", "here"] 

See: Python docs on List Comprehension
A good 2 second explanation of list comprehension.

I came to add:

map(str.strip, string.split(',')) 

but saw it had already been mentioned by Jason Orendorff in a comment.

Reading Glenn Maynard's comment on the same answer suggesting list comprehensions over map I started to wonder why. I assumed he meant for performance reasons, but of course he might have meant for stylistic reasons, or something else (Glenn?).

So a quick (possibly flawed?) test on my box (Python 2.6.5 on Ubuntu 10.04) applying the three methods in a loop revealed:

$ time ./list_comprehension.py # [word.strip() for word in string.split(',')] real 0m22.876s $ time ./map_with_lambda.py # map(lambda s: s.strip(), string.split(',')) real 0m25.736s $ time ./map_with_str.strip.py # map(str.strip, string.split(',')) real 0m19.428s 

making map(str.strip, string.split(',')) the winner, although it seems they are all in the same ballpark.

Certainly though map (with or without a lambda) should not necessarily be ruled out for performance reasons, and for me it is at least as clear as a list comprehension.

Split using a regular expression. Note I made the case more general with leading spaces. The list comprehension is to remove the null strings at the front and back.

>>> import re >>> string = " blah, lots , of , spaces, here " >>> pattern = re.compile("^\s+|\s*,\s*|\s+$") >>> print([x for x in pattern.split(string) if x]) ['blah', 'lots', 'of', 'spaces', 'here'] 

This works even if ^\s+ doesn't match:

>>> string = "foo, bar " >>> print([x for x in pattern.split(string) if x]) ['foo', 'bar'] >>> 

Here's why you need ^\s+:

>>> pattern = re.compile("\s*,\s*|\s+$") >>> print([x for x in pattern.split(string) if x]) [' blah', 'lots', 'of', 'spaces', 'here'] 

See the leading spaces in blah?

Clarification: above uses the Python 3 interpreter, but results are the same in Python 2.

Just remove the white space from the string before you split it.

mylist = my_string.replace(' ','').split(',') 

I know this has already been answered, but if you end doing this a lot, regular expressions may be a better way to go:

>>> import re >>> re.sub(r'\s', '', string).split(',') ['blah', 'lots', 'of', 'spaces', 'here'] 

The \s matches any whitespace character, and we just replace it with an empty string ''. You can find more info here:

map(lambda s: s.strip(), mylist) would be a little better than explicitly looping. Or for the whole thing at once: map(lambda s:s.strip(), string.split(','))

import re result=[x for x in re.split(',| ',your_string) if x!=''] 

this works fine for me.

re (as in regular expressions) allows splitting on multiple characters at once:

$ string = "blah, lots , of , spaces, here " $ re.split(', ',string) ['blah', 'lots ', ' of ', ' spaces', 'here '] 

This doesn't work well for your example string, but works nicely for a comma-space separated list. For your example string, you can combine the re.split power to split on regex patterns to get a "split-on-this-or-that" effect.

$ re.split('[, ]',string) ['blah', '', 'lots', '', '', '', '', 'of', '', '', '', 'spaces', '', 'here', ''] 

Unfortunately, that's ugly, but a filter will do the trick:

$ filter(None, re.split('[, ]',string)) ['blah', 'lots', 'of', 'spaces', 'here'] 

Voila!

s = 'bla, buu, jii' sp = [] sp = s.split(',') for st in sp: print st 

import re mylist = [x for x in re.compile('\s*[,|\s+]\s*').split(string)] 

Simply, comma or at least one white spaces with/without preceding/succeeding white spaces.

Please try!

Instead of splitting the string first and then worrying about white space you can first deal with it and then split it

string.replace(" ", "").split(",")