Case insensitive regular expression without re.compile?

Mat_42974 0
Viewed 467556

In Python, I can compile a regular expression to be case-insensitive using re.compile:

>>> s = 'TeSt'
>>> casesensitive = re.compile('test')
>>> ignorecase = re.compile('test', re.IGNORECASE)
>>> 
>>> print casesensitive.match(s)
None
>>> print ignorecase.match(s)
<_sre.SRE_Match object at 0x02F0B608>

Is there a way to do the same, but without using re.compile. I can't find anything like Perl's i suffix (e.g. m/test/i) in the documentation.

case-insensitive case-sensitive python regex
9 Answers

Pass re.IGNORECASE to the flags param of search, match, or sub:

re.search('test', 'TeSt', re.IGNORECASE)
re.match('test', 'TeSt', re.IGNORECASE)
re.sub('test', 'xxxx', 'Testing', flags=re.IGNORECASE)
Michael_Haren_290

To perform case-insensitive operations, supply re.IGNORECASE

>>> import re
>>> test = 'UPPER TEXT, lower text, Mixed Text'
>>> re.findall('text', test, flags=re.IGNORECASE)
['TEXT', 'text', 'Text']

and if we want to replace text matching the case...

>>> def matchcase(word):
        def replace(m):
            text = m.group()
            if text.isupper():
                return word.upper()
            elif text.islower():
                return word.lower()
            elif text[0].isupper():
                return word.capitalize()
            else:
                return word
        return replace

>>> re.sub('text', matchcase('word'), test, flags=re.IGNORECASE)
'UPPER WORD, lower word, Mixed Word'
user_69091820

For Case insensitive regular expression(Regex): There are two ways by adding in your code:

  1. flags=re.IGNORECASE

    Regx3GList = re.search("(WCDMA:)((\d*)(,?))*", txt, **re.IGNORECASE**)

  2. The case-insensitive marker (?i)

    Regx3GList = re.search("**(?i)**(WCDMA:)((\d*)(,?))*", txt)
user_132948340 
#'re.IGNORECASE' for case insensitive results short form re.I
#'re.match' returns the first match located from the start of the string. 
#'re.search' returns location of the where the match is found 
#'re.compile' creates a regex object that can be used for multiple matches

 >>> s = r'TeSt'   
 >>> print (re.match(s, r'test123', re.I))
 <_sre.SRE_Match object; span=(0, 4), match='test'>
 # OR
 >>> pattern = re.compile(s, re.I)
 >>> print(pattern.match(r'test123'))
 <_sre.SRE_Match object; span=(0, 4), match='test'>
user_45846720

If you would like to replace but still keeping the style of previous str. It is possible.

For example: highlight the string "test asdasd TEST asd tEst asdasd".

sentence = "test asdasd TEST asd tEst asdasd"
result = re.sub(
  '(test)', 
  r'<b>\1</b>',  # \1 here indicates first matching group.
  sentence, 
  flags=re.IGNORECASE)

test asdasd TEST asd tEst asdasd

user_38318450
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