How to capture repeated occurrence using python 3 regex

Question

Consider sentence : W U T Sample A B C D

I'm trying to use re.groups after re.search to fetch A, B, C, D (letters in caps after 'Sample'). There could be variable number of letters

Few unsuccessful attempts :

A = re.search('Sample\s([A-Z])\s*([A-Z])*', 'W U T Sample A B C D')
A.groups()
('A', 'B')

A = re.search('Sample\s([A-Z])(\s*([A-Z]))*', 'W U T Sample A B C D')
A.groups()
('A', ' D', 'D')

A = re.search('Sample\s([A-Z])(?:\s*([A-Z]))*', 'W U T Sample A B C D')
A.groups()
('A', 'D')

I'm expecting A.groups() to give ('A', 'B', 'C', 'D')

Taking another example, 'XSS 55 D W Sample R G Y BH' should give the output ('R', 'G', 'Y', 'B', 'H')

@CodeManiac Useful tool, but the example regex mentioned does not give ('R', 'G', 'Y', 'B', 'H') for 'XSS 55 D W Sample R G Y BH'. B and H are considered one, which is different from what I want — abhivij
– abhivij, Commented Mar 31, 2019 at 5:54

Tim Biegeleisen · Accepted Answer · 2019-03-31 07:00:06Z

1

Most regex engines, including Python's, will overwrite a repeating capture group. So, the repeating capture group you see will just be the final one, and your current approach will not work. As a workaround, we can try first isolating the substring you want, and then applying re.findall:

input = "W U T Sample A B C D"
text = re.search(r'Sample\s([A-Z](?:\s*[A-Z])*)', input).group(1)  # A B C D
result = re.findall(r'[A-Z]', text)
print(result)

['A', 'B', 'C', 'D']

edited Mar 31, 2019 at 7:00

answered Mar 31, 2019 at 4:01

Tim Biegeleisen

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1 Comment

abhivij Over a year ago

Thanks, I suppose two steps would be involved for this.

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