Case insensitive regular expression without re.compile?

Question

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.

Solution 1

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)

Solution 2

You can also perform case insensitive searches using search/match without the IGNORECASE flag (tested in Python 2.7.3):

re.search(r'(?i)test', 'TeSt').group()    ## returns 'TeSt'
re.match(r'(?i)test', 'TeSt').group()     ## returns 'TeSt'

Solution 3

The case-insensitive marker, (?i) can be incorporated directly into the regex pattern:

>>> import re
>>> s = 'This is one Test, another TEST, and another test.'
>>> re.findall('(?i)test', s)
['Test', 'TEST', 'test']

Solution 4

You can also define case insensitive during the pattern compile:

pattern = re.compile('FIle:/+(.*)', re.IGNORECASE)

Solution 5

In imports

import re

In run time processing:

RE_TEST = r'test'
if re.match(RE_TEST, 'TeSt', re.IGNORECASE):

It should be mentioned that not using re.compile is wasteful. Every time the above match method is called, the regular expression will be compiled. This is also faulty practice in other programming languages. The below is the better practice.

In app initialization:

self.RE_TEST = re.compile('test', re.IGNORECASE)

In run time processing:

if self.RE_TEST.match('TeSt'):

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