How do I trim whitespace?

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()

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

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

This 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

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"

(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'

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, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, , , , \r, , \0, ff dd \n invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com 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, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com 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,  jim.somedude@blahblah.com, dd invites,subscribed,, master, dd invites,subscribed, ff dd invites, subscribed, alumni spring 2012 deck: https: www.dropbox.com 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, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com 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, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com 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"

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.