在Python中，我可以使用re.compile将正则表达式编译为不区分大小写:
>>> 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>
是否有一种方法可以做同样的事情，但不使用re.compile。我在文档中找不到任何类似Perl的I后缀(例如m/test/ I)的东西。
当前回答
将re.IGNORECASE传递给search、match或sub的flags参数:
re.search('test', 'TeSt', re.IGNORECASE)
re.match('test', 'TeSt', re.IGNORECASE)
re.sub('test', 'xxxx', 'Testing', flags=re.IGNORECASE)
其他回答
(?i)用以下有效标志匹配模式的剩余部分:不区分大小写匹配(忽略[a-zA-Z]的大小写)
>>> import pandas as pd
>>> s = pd.DataFrame({ 'a': ["TeSt"] })
>>> r = s.replace(to_replace=r'(?i)test', value=r'TEST', regex=True)
>>> print(r)
a
0 TEST
要执行不区分大小写的操作，请提供re.IGNORECASE
>>> import re
>>> test = 'UPPER TEXT, lower text, Mixed Text'
>>> re.findall('text', test, flags=re.IGNORECASE)
['TEXT', 'text', 'Text']
如果我们想替换匹配大小写的文本…
>>> 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'
#'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'>
将re.IGNORECASE传递给search、match或sub的flags参数:
re.search('test', 'TeSt', re.IGNORECASE)
re.match('test', 'TeSt', re.IGNORECASE)
re.sub('test', 'xxxx', 'Testing', flags=re.IGNORECASE)
你也可以使用不带IGNORECASE标志的搜索/匹配执行不区分大小写的搜索(在Python 2.7.3中测试):
re.search(r'(?i)test', 'TeSt').group() ## returns 'TeSt'
re.match(r'(?i)test', 'TeSt').group() ## returns 'TeSt'
