上下文正则表达式拆分

Question

I want to split a string on ', ' but not on ',, '

So with input 'abc,, def, ghi' I want output

[ 'abc,, def', 'ghi' ]

I tried re.split("(?:[^,]), ",'abc,, def, ghi' ) but it removed the 'f'

is there a way to do this?

Answer 1

I'd recommend using regex lookarounds:

>>> re.split('(?<!,),(?=\s)', text)
['abc,, def', ' ghi']

Details

(?<!   # negative lookbehind
,      # comma
)
,      
(?=    # positive lookahead
\s     # whitespace
)

Semantically, this means "split on a single comma only (comma that is not preceded or succeeded by any commas)."