How to regexp match groups at end of variable length comma separated string

Question

I have a need to get the last two elements of a comma separated string of any number of elements, that also starts with a specified value.

Here is an example of how I expect it to work.

def process(pattern, string):
  part1, part2 = None, None
  match = re.search(pattern, string)
  if match:
    part1 = match.group(1)
    part2 = match.group(2)
return part1, part2

regex_search = ?
string1 = must,have,blah,blah,blah,blah,grab,this
string2 = must,have,grab,that
string3 = wrong,have,drop,this

print(process(regex_search, string1)
print(process(regex_search, string2)
print(process(regex_search, string3)

result is supposed to be

('grab', 'this')
('grab', 'that')
(None, None)

My regexp and what its currently getting

regex_search = '^must,have,(.*)\\,(.*)$'

('blah,blah,blah,blah,grab', 'this')
('grab', 'that')
(None, None)

Edit: Thanks Wiktor!! Solution below.

^must,have,(?:.*,)?(.*),(.*)$

Maybe ^must,have,(?:.*,)?(.*),(.*)$? Or ^must,have,(?:.*,)?([^,]*),([^,]*)$ — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Oct 13, 2022 at 17:39

chugaister · Accepted Answer · 2022-10-13 17:38:51Z

4

Try this:

,([^,]*),([^,]*$)

It should return only two last groups separated by commas

answered Oct 13, 2022 at 17:38

chugaister

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Comments

lroth · Accepted Answer · 2022-10-13 18:06:59Z

1

instead of regex we can also use a for loop to grap the required data.

lst = ['must,have,blah,blah,blah,blah,grab,this','must,have,grab,that','wrong,have,drop,this']
for item in lst:
    if item.startswith('must'):
        res = item.split(',')[-2:]
        print(res)

result:

['grab', 'this']
['grab', 'that']

answered Oct 13, 2022 at 18:06

lroth

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