split by comma if comma not in between brackets while allowing characters to be outside the brackets with in the same comma split

Question

I have this python script. That uses some regular expression. I want to split the string s, but commas while ignoring any commas that exists within the brackets.

s = """aa,bb,(cc,dd),m(ee,ff)"""
splits = re.split(r'\s*(\([^)]*\)|[^,]+)', s, re.M|re.S)
print('\n'.join(splits))
Actual output:
    aa
    ,
    bb
    ,
    (cc,dd)
    ,
    m(ee
    ,
    ff)
Desired output: 
    aa
    bb
    (cc,dd)
    m(ee,ff)

So I can't make it handle having text outside the brackets. Was hoping someone could help me out.

I'm not, that's what I want. It's outputting m(ee\n ,\n ff)\n instead. — h33, Mar 12 '19 at 06:00
sorry, that was a mistake I made while editting. Fixed it now — h33, Mar 12 '19 at 06:01
Possible duplicate of [How to split by commas that are not within parentheses?](https://stackoverflow.com/questions/26633452/how-to-split-by-commas-that-are-not-within-parentheses) — Austin, Mar 12 '19 at 06:05
I originally wanted to consider both, but then decided to just do brackets to make it siimpler. — h33, Mar 12 '19 at 06:05
I looked at that one and it doesn't work for keeping the stuff outside the brackets in the same split. — h33, Mar 12 '19 at 06:06

score 2 · Accepted Answer · answered Mar 12 '19 at 06:07

You may use this regex with a lookahead for split:

>>> s = """aa,bb,(cc,dd),m(ee,ff)"""
>>> print ( re.split(r',(?![^()]*\))', s) )
['aa', 'bb', '(cc,dd)', 'm(ee,ff)']

RegEx Demo

RegEx Details:

,: Match a comma
(?![^()]*\)): A negative lookahead assertion that makes sure we don't match comma inside (...) by asserting that there is no ) ahead after 0 or more not bracket characters.

CertainPerformance · Answer 2 · 2019-03-12T06:19:21.190

1

Consider using findall instead - repeat a group that matches (s followed by non-) characters, followed by ), or matches non-, characters:

s = """aa,bb,m(cc,dd)"""
matches = re.findall(r'(?:\([^(]+\)|[^,])+', s, re.M|re.S)
print('\n'.join(matches))

If speed is an issue, you can make it a bit more efficient by putting ( in the other negative character set, and alternating it first:

(?:[^(,]+|\([^(]+\))+

edited Mar 12 '19 at 06:19

answered Mar 12 '19 at 06:05

CertainPerformance

356,069
52
309
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Check no of steps it takes on https://regex101.com/r/UXdHRe/2 (272 steps) vs my suggested split regex (146 steps). – anubhava Mar 12 '19 at 06:47

score 0 · Answer 3 · answered Mar 05 '23 at 17:03

I needed to do something similar, but I also had nested brackets. The proposed regex expressions do NOT handle nesting.

I couldn't find a regex solution, but here is a python function solution that achieves the same thing:

def comma_split(text: str) -> list[str]:
    flag = 0
    buffer = ""
    result = []
    for char_ in text:
        if char_ == "[":
            flag += 1
        elif char_ == "]":
            flag -= 1
        elif char_ == "," and flag == 0:
            result.append(buffer)
            buffer = ""
            continue
        buffer += char_
    if buffer:
        result.append(buffer)
    return result

score -1 · Answer 4 · answered Mar 12 '19 at 06:28

-1

try : r',([^,()][(][^()][)][^,])|([^,]+)'

tested on regex101 : https://regex101.com/r/pJxRwQ/1

answered Mar 12 '19 at 06:28

shikai ng

137
3

split by comma if comma not in between brackets while allowing characters to be outside the brackets with in the same comma split

4 Answers4