How do I trim whitespace?

Is there a Python function that will trim whitespace (spaces and tabs) from a string?

So that given input " \t example string\t " becomes "example string".

15 Answers

For whitespace on both sides, use str.strip:

s = " \t a string example\t " s = s.strip() 

For whitespace on the right side, use str.rstrip:

s = s.rstrip() 

For whitespace on the left side, use str.lstrip:

s = s.lstrip() 

To strip arbitrary characters, one can provide an argument to any of these functions, like this:

s = s.strip(' \t\n\r') 

That will strip any space, \t, \n, or \r characters from both sides of the string.

The examples above only remove strings from the left-hand and right-hand sides of strings. If you want to also remove characters from the middle of a string, try re.sub:

import re print(re.sub('[\s+]', '', s)) 

That should print out:

astringexample 

In Python trim methods are named strip:

str.strip() # trim str.lstrip() # left trim str.rstrip() # right trim 

For leading and trailing whitespace:

s = ' foo \t ' print s.strip() # prints "foo" 

Otherwise, a regular expression works:

import re pat = re.compile(r'\s+') s = ' \t foo \t bar \t ' print pat.sub('', s) # prints "foobar" 

You can also use very simple, and basic function: str.replace(), works with the whitespaces and tabs:

>>> whitespaces = " abcd ef gh ijkl " >>> tabs = " abcde fgh ijkl" >>> print whitespaces.replace(" ", "") abcdefghijkl >>> print tabs.replace(" ", "") abcdefghijkl 

Simple and easy.

#how to trim a multi line string or a file s=""" line one \tline two\t line three """ #line1 starts with a space, #2 starts and ends with a tab, #3 ends with a space. s1=s.splitlines() print s1 [' line one', '\tline two\t', 'line three '] print [i.strip() for i in s1] ['line one', 'line two', 'line three'] #more details: #we could also have used a forloop from the begining: for line in s.splitlines(): line=line.strip() process(line) #we could also be reading a file line by line.. e.g. my_file=open(filename), or with open(filename) as myfile: for line in my_file: line=line.strip() process(line) #moot point: note splitlines() removed the newline characters, we can keep them by passing True: #although split() will then remove them anyway.. s2=s.splitlines(True) print s2 [' line one\n', '\tline two\t\n', 'line three '] 

No one has posted these regex solutions yet.

Matching:

>>> import re >>> p=re.compile('\\s*(.*\\S)?\\s*') >>> m=p.match(' \t blah ') >>> m.group(1) 'blah' >>> m=p.match(' \tbl ah \t ') >>> m.group(1) 'bl ah' >>> m=p.match(' \t ') >>> print m.group(1) None 

Searching (you have to handle the "only spaces" input case differently):

>>> p1=re.compile('\\S.*\\S') >>> m=p1.search(' \tblah \t ') >>> m.group() 'blah' >>> m=p1.search(' \tbl ah \t ') >>> m.group() 'bl ah' >>> m=p1.search(' \t ') >>> m.group() Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'NoneType' object has no attribute 'group' 

If you use re.sub, you may remove inner whitespace, which could be undesirable.

Whitespace includes space, tabs and CRLF. So an elegant and one-liner string function we can use is translate.

' hello apple'.translate(None, ' \n\t\r')

OR if you want to be thorough

import string ' hello apple'.translate(None, string.whitespace) 

(re.sub(' +', ' ',(my_str.replace('\n',' ')))).strip()

This will remove all the unwanted spaces and newline characters. Hope this help

import re my_str = ' a b \n c ' formatted_str = (re.sub(' +', ' ',(my_str.replace('\n',' ')))).strip() 

This will result :

' a      b \n c ' will be changed to 'a b c'

 something = "\t please_ \t remove_ all_ \n\n\n\nwhitespaces\n\t " something = "".join(something.split()) 

output:

please_remove_all_whitespaces

Adding Le Droid's comment to the answer. To separate with a space:

 something = "\t please \t remove all extra \n\n\n\nwhitespaces\n\t " something = " ".join(something.split()) 

output:

please remove all extra whitespaces

Having looked at quite a few solutions here with various degrees of understanding, I wondered what to do if the string was comma separated...

the problem

While trying to process a csv of contact information, I needed a solution this problem: trim extraneous whitespace and some junk, but preserve trailing commas, and internal whitespace. Working with a field containing notes on the contacts, I wanted to remove the garbage, leaving the good stuff. Trimming out all the punctuation and chaff, I didn't want to lose the whitespace between compound tokens as I didn't want to rebuild later.

regex and patterns: [\s_]+?\W+

The pattern looks for single instances of any whitespace character and the underscore ('_') from 1 to an unlimited number of times lazily (as few characters as possible) with [\s_]+? that come before non-word characters occurring from 1 to an unlimited amount of time with this: \W+ (is equivalent to [^a-zA-Z0-9_]). Specifically, this finds swaths of whitespace: null characters (\0), tabs (\t), newlines (\n), feed-forward (\f), carriage returns (\r).

I see the advantage to this as two-fold:

1. that it doesn't remove whitespace between the complete words/tokens that you might want to keep together;

2. Python's built in string method strip()doesn't deal inside the string, just the left and right ends, and default arg is null characters (see below example: several newlines are in the text, and strip() does not remove them all while the regex pattern does). text.strip(' \n\t\r')

This goes beyond the OPs question, but I think there are plenty of cases where we might have odd, pathological instances within the text data, as I did (some how the escape characters ended up in some of the text). Moreover, in list-like strings, we don't want to eliminate the delimiter unless the delimiter separates two whitespace characters or some non-word character, like '-,' or '-, ,,,'.

NB: Not talking about the delimiter of the CSV itself. Only of instances within the CSV where the data is list-like, ie is a c.s. string of substrings.

Full disclosure: I've only been manipulating text for about a month, and regex only the last two weeks, so I'm sure there are some nuances I'm missing. That said, for smaller collections of strings (mine are in a dataframe of 12,000 rows and 40 odd columns), as a final step after a pass for removal of extraneous characters, this works exceptionally well, especially if you introduce some additional whitespace where you want to separate text joined by a non-word character, but don't want to add whitespace where there was none before.

An example:

import re text = "\"portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, , ,dd invites,subscribed,, master, , , , dd invites,subscribed, , , , \r, , \0, ff dd \n invites, subscribed, , , , , alumni spring 2012 deck: https: s, \n i69rpofhfsp9t7c practice 20ignition - 20june \t\n .2134.pdf 2109 \n\n\n\nklkjsdf\"" print(f"Here is the text as formatted:\n{text}\n") print() print("Trimming both the whitespaces and the non-word characters that follow them.") print() trim_ws_punctn = re.compile(r'[\s_]+?\W+') clean_text = trim_ws_punctn.sub(' ', text) print(clean_text) print() print("what about 'strip()'?") print(f"Here is the text, formatted as is:\n{text}\n") clean_text = text.strip(' \n\t\r') # strip out whitespace? print() print(f"Here is the text, formatted as is:\n{clean_text}\n") print() print("Are 'text' and 'clean_text' unchanged?") print(clean_text == text) 

This outputs:

Here is the text as formatted: "portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, , ,dd invites,subscribed,, master, , , , dd invites,subscribed, ,, , , ff dd invites, subscribed, , , , , alumni spring 2012 deck: https: s, i69rpofhfsp9t7c practice 20ignition - 20june .2134.pdf 2109 klkjsdf" using regex to trim both the whitespaces and the non-word characters that follow them. "portfolio, derp, hello-world, hello-, world, founders, mentors, ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, ff, series a, exit, general mailing, fr, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, , dd invites,subscribed,, master, dd invites,subscribed, ff dd invites, subscribed, alumni spring 2012 deck: https: s, i69rpofhfsp9t7c practice 20ignition 20june 2134.pdf 2109 klkjsdf" Very nice. What about 'strip()'? Here is the text, formatted as is: "portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, , ,dd invites,subscribed,, master, , , , dd invites,subscribed, ,, , , ff dd invites, subscribed, , , , , alumni spring 2012 deck: https: s, i69rpofhfsp9t7c practice 20ignition - 20june .2134.pdf 2109 klkjsdf" Here is the text, after stipping with 'strip': "portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, , ,dd invites,subscribed,, master, , , , dd invites,subscribed, ,, , , ff dd invites, subscribed, , , , , alumni spring 2012 deck: https: s, i69rpofhfsp9t7c practice 20ignition - 20june .2134.pdf 2109 klkjsdf" Are 'text' and 'clean_text' unchanged? 'True' 

So strip removes one whitespace from at a time. So in the OPs case, strip() is fine. but if things get any more complex, regex and a similar pattern may be of some value for more general settings.

see it in action

If using Python 3: In your print statement, finish with sep="". That will separate out all of the spaces.

EXAMPLE:

txt="potatoes" print("I love ",txt,"",sep="") 

This will print: I love potatoes.

Instead of: I love potatoes .

In your case, since you would be trying to get ride of the \t, do sep="\t"

try translate

>>> import string >>> print '\t\r\n hello \r\n world \t\r\n' hello world >>> tr = string.maketrans(string.whitespace, ' '*len(string.whitespace)) >>> '\t\r\n hello \r\n world \t\r\n'.translate(tr) ' hello world ' >>> '\t\r\n hello \r\n world \t\r\n'.translate(tr).replace(' ', '') 'helloworld' 

If you want to trim the whitespace off just the beginning and end of the string, you can do something like this:

some_string = " Hello, world!\n " new_string = some_string.strip() # new_string is now "Hello, world!" 

This works a lot like Qt's QString::trimmed() method, in that it removes leading and trailing whitespace, while leaving internal whitespace alone.

But if you'd like something like Qt's QString::simplified() method which not only removes leading and trailing whitespace, but also "squishes" all consecutive internal whitespace to one space character, you can use a combination of .split() and " ".join, like this:

some_string = "\t Hello, \n\t world!\n " new_string = " ".join(some_string.split()) # new_string is now "Hello, world!" 

In this last example, each sequence of internal whitespace replaced with a single space, while still trimming the whitespace off the start and end of the string.

Generally, I am using the following method:

>>> myStr = "Hi\n Stack Over \r flow!" >>> charList = [u"\u005Cn",u"\u005Cr",u"\u005Ct"] >>> import re >>> for i in charList: myStr = re.sub(i, r"", myStr) >>> myStr 'Hi Stack Over flow' 

Note: This is only for removing "\n", "\r" and "\t" only. It does not remove extra spaces.

This will remove all whitespace and newlines from both the beginning and end of a string:

>>> s = " \n\t \n some \n text \n " >>> re.sub("^\s+|\s+$", "", s) >>> "some \n text"