Python Regex stops after first "|" match [closed]

Question

p = re.compile("[AG].{2}[ATG|ATA|AAG].{1}G")
regex_result = p.search('ZZZAXXATGXGZZZ')
regex_result.group()
'AXXATG'

I was expecting AXXATGXG instead.

Answer 1

Use a grouping construct (...) rather than a character class [...] around the alternatives:

p = re.compile("[AG].{2}(?:ATG|ATA|AAG).G")
                        ^^^^^^^^^^^^^^^  

The (?:ATG|ATA|AAG) matches 3 sequences: either a ATG, or ATA or AAG. The [ATG|ATA|AAG] character class matches 1 char, either A, T, G or |.

Note the {1} is redundant and can be removed.

Python:

import re
p = re.compile("[AG].{2}(?:ATG|ATA|AAG).G")
regex_result = p.search('ZZZAXXATGXGZZZ')
print(regex_result.group())
# => AXXATGXG

See IDEONE demo