How do I trim whitespace?

Question

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

Example: \t example string\t → example string

Answer 1

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.

Answer 2

Whitespace on both sides:

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

Whitespace on the right side:

s = s.rstrip()

Whitespace on the left side:

s = s.lstrip()

As thedz points out, 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 the left-hand side, right-hand side, or 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