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.
