python - 正则表达式:如何按 "="拆分而不是按 "!="拆分

Question

>> s1 = "a=b"
>> s2 = "a!=b"

>> re.compile("SOMTHING").split(s1)
>> # I expect ['a','1']

>> re.compile("SOMTHING").split(s2)
>> # I expect ['a!=1'] and NOT ['a!,'1'] 

我尝试了 compile([^!]=).split(s2) 但这不起作用并给出 ['','1']

我怎样才能做到这一点？

Answer 1

您可以使用 negative lookbehind assertion为了这。

>>> s1 = "a=b"
>>> s2 = "a!=b"
>>> r = re.compile(r"(?<!!)=")
>>> r.split(s1)
['a', 'b']
>>> r.split(s2)
['a!=b']

根据您的输入，您可能还需要展望 future :

>>> s3 = "a==b"  # I guess you wouldn't want to split that
>>> r.split(s3)
['a', '', 'b']
>>> r = re.compile(r"(?<![!=])=(?!=)")
>>> r.split(s3)
['a==b']