String split using regex with pattern present in text

Question

I have many string that I need to split by commas. Example:

myString = r'test,Test,NEAR(this,that,DISTANCE=4),test again,"another test"'
myString = r'test,Test,FOLLOWEDBY(this,that,DISTANCE=4),test again,"another test"'

My desired output would be:

["test", "Test", "NEAR(this,that,DISTANCE=4)", "test again", """another test"""] #list length = 5

I can't figure out how to keep the commas between "this,that,DISTANCE" in one item. I tried this:

l = re.compile(r',').split(myString) # matches all commas
l = re.compile(r'(?<!\(),(?=\))').split(myString) # (negative lookback/lookforward) - no matches at all

Any ideas? Let's say the list of allowed "functions" is defined as:

f = ["NEAR","FOLLOWEDBY","AND","OR","MAX"]

Possible duplicate of How to split by commas that are not within parentheses? — Austin
– Austin, Commented Nov 22, 2018 at 14:20

Wiktor Stribiżew · Accepted Answer · 2018-11-22 14:20:15Z

2

You may use

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

See the regex demo.

The (?:\([^()]*\)|[^,])+ pattern matches one or more occurrences of any substring between parentheses with no ( and ) in them or any char other than ,.

See the Python demo:

import re
rx = r"(?:\([^()]*\)|[^,])+"
s = 'test,Test,NEAR(this,that,DISTANCE=4),test again,"another test"'
print(re.findall(rx, s))
# => ['test', 'Test', 'NEAR(this,that,DISTANCE=4)', 'test again', '"another test"']

answered Nov 22, 2018 at 14:20

Wiktor Stribiżew

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timgeb · Accepted Answer · 2018-11-22 14:26:17Z

If explicitly want to specify which strings count as functions, you need to build the regex dynamically. Otherwise, go with Wiktor's solution.

>>> functions = ["NEAR","FOLLOWEDBY","AND","OR","MAX"]
>>> funcs = '|'.join('{}\([^\)]+\)'.format(f) for f in functions)
>>> regex = '({})|,'.format(funcs)
>>>
>>> myString1 = 'test,Test,NEAR(this,that,DISTANCE=4),test again,"another test"'
>>> list(filter(None, re.split(regex, myString1)))
['test', 'Test', 'NEAR(this,that,DISTANCE=4)', 'test again', '"another test"']
>>> myString2 = 'test,Test,FOLLOWEDBY(this,that,DISTANCE=4),test again,"another test"'
>>> list(filter(None, re.split(regex, myString2)))
['test',
 'Test',
 'FOLLOWEDBY(this,that,DISTANCE=4)',
 'test again',
 '"another test"']

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