Splitting string and removing whitespace Python

Question

I would like to split a String by comma ',' and remove whitespace from the beginning and end of each split.

For example, if I have the string:

"QVOD, Baidu Player"

I would like to split and strip to:

['QVOD', 'Baidu Player']

Is there an elegant way of doing this? Possibly using a list comprehension?

Possible duplicate of [this question](http://stackoverflow.com/questions/761804/trimming-a-string-in-python/761825#761825). Not completely, but you can find all the answers you need there. — Kraay89, Jan 21 '14 at 14:50

Slater Victoroff · Accepted Answer · 2014-01-21T15:01:37.913

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Python has a spectacular function called split that will keep you from having to use a regex or something similar. You can split your string by just calling my_string.split(delimiter)

After that python has a strip function which will remove all whitespace from the beginning and end of a string.

[item.strip() for item in my_string.split(',')]

Benchmarks for the two methods are below:

>>> import timeit
>>> timeit.timeit('map(str.strip, "QVOD, Baidu Player".split(","))', number=100000)
0.3525350093841553
>>> timeit.timeit('map(stripper, "QVOD, Baidu Player".split(","))','stripper=str.strip', number=100000)
0.31575989723205566
>>> timeit.timeit("[item.strip() for item in 'QVOD, Baidu Player'.split(',')]", number=100000)
0.246596097946167

So the list comp is about 33% faster than the map.

Probably also worth noting that as far as being "pythonic" goes, Guido himself votes for the LC. http://www.artima.com/weblogs/viewpost.jsp?thread=98196

edited Jan 21 '14 at 15:01

answered Jan 21 '14 at 14:47

Slater Victoroff

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@DSM Whoops, my bad. Thanks for catching that. – Slater Victoroff Jan 21 '14 at 14:52
Thanks I tried something like this already and each part `QVOD` ect.. is placed on a new line. The answer below works well as everything is in a list. – Daniel Pilch Jan 21 '14 at 14:53
3

@DanielPilch: both methods produce the same list. – DSM Jan 21 '14 at 14:55
@SlaterTyranus Please check the updated code. This might perform almost as fast as LC. – thefourtheye Jan 21 '14 at 14:57
@thefourtheye It's faster than the other version, but still noticeably slower than the LC – Slater Victoroff Jan 21 '14 at 14:59
@SlaterTyranus Please not that it varies from machine to machine. Check the results on my machine :) – thefourtheye Jan 21 '14 at 15:00
Yep you're right, I was printing item and not creating a list from the comprehension `categories = [item.strip() for item in my_string.split(',')]` silly mistake and yes it is faster, thanks! – Daniel Pilch Jan 21 '14 at 15:00
@StevenRumbalski The arguments between LC's and the `map`, `reduce`, `filter` functions are pretty well established, so I figured it didn't need much discussion, but linked to the article to try to cover for that aspect. – Slater Victoroff Jan 21 '14 at 15:14

thefourtheye · Answer 2 · 2014-01-21T14:56:50.190

4

A little functional approach. split function, splits the string based on , and the each and every element will be stripped by str.strip, by map.

>>> stripper = str.strip
>>> map(stripper, "QVOD, Baidu Player".split(","))
['QVOD', 'Baidu Player']

Little timing comparison

import timeit
stripper = str.strip
print timeit.timeit('map(stripper, "QVOD, Baidu Player".split(","))', "from __main__ import stripper", number=100000)
print timeit.timeit("[item.strip() for item in 'QVOD, Baidu Player'.split(',')]", number=100000)

Output on my machine

0.553178071976
0.569463968277

So, both the List comprehension method and map method perform almost the same.

edited Jan 21 '14 at 14:56

answered Jan 21 '14 at 14:49

thefourtheye

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Why are you assigning `str.strip` to a variable? Why not pass it directly -`map(str.strip, "QVOD, Baidu Player".split(","))` – pyrospade Jan 21 '14 at 14:59
@pyrospade That doesn't have to got from `str` everytime. So, little performance gain :) – thefourtheye Jan 21 '14 at 15:01
@thefourtheye Really? I would imagine that when you pass `str.strip` to `map(function, sequence)` it is getting assigned to the `function` parameter and used locally as a variable there. – pyrospade Jan 21 '14 at 15:04
@thefourtheye What version of python are you running? – Slater Victoroff Jan 21 '14 at 15:05

Splitting string and removing whitespace Python

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