I have a Python list of strings. I want to do the regex search on each element, filtering only those elements where I managed to capture the regex group. I think I can do the regex search only once using the walrus operator from Python 3.8. So far I have:
attacks = [match for attack in attacks if (match := re.search(r"(([0-9]+d[sS]+))", attack).group() is not None)]
The logic is: I take the found group if the regex search returned anything, which means it is not None. The problem is, the bevahiour is weird – I can print()
before this list comprehension, the program finishes with code 0, but there is no result and print()
after the list comprehension does not work. What am I doing wrong?
EDIT:
Full code:
text = "Speed 30 ft. Melee short sword +3 (1d6+1/19-20) Ranged light crossbow +3 (1d8/19-20) Special Attacks sneak attack +1d6 Spell-Like Abilities (CL 1st) " if attacks: attacks = attacks.group().split(")") attacks = [match for attack in attacks if (match := re.search(r"(([0-9]+d[sS]+))", attack).group() is not None)]
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Answer
Remove the .group() is not None
. If there isn’t any match, re.search()
returns None
and exception is thrown:
import re attacks = ['(7dW)', 'xxx'] attacks = [match for attack in attacks if (match := re.search(r"(([0-9]+d[sS]+))", attack))] print(attacks)
Prints:
[<re.Match object; span=(0, 5), match='(7dW)'>]