If any strings in a list match regex

Given that I am not allowed to comment yet, I wanted to provide a small correction to MrAlexBailey's answer, and also answer nat5142's question. Correct form would be:

r = re.compile('.*search.*')
if any(r.match(line) for line in output):
    do_stuff()

If you desire to find the matched string, you would do:

lines_to_log = [line for line in output if r.match(line)]

In addition, if you want to find all lines that match any compiled regular expression in a list of compiled regular expressions r=[r1,r2,...,rn], you can use:

lines_to_log = [line for line in output if any(reg_ex.match(line) for reg_ex in r)]

Starting Python 3.8, and the introduction of assignment expressions (PEP 572) (:= operator), we can also capture a witness of an any expression when a match is found and directly use it:

# pattern = re.compile('.*search.*')
# items = ['hello', 'searched', 'world', 'still', 'searching']
if any((match := pattern.match(x)) for x in items):
  print(match.group(0))
# 'searched'

For each item, this:

• Applies the regex search (pattern.match(x))
• Assigns the result to a match variable (either None or a re.Match object)
• Applies the truth value of match as part of the any expression (None -> False, Match -> True)
• If match is None, then the any search loop continues
• If match has captured a group, then we exit the any expression which is considered True and the match variable can be used within the condition's body

You can use the builtin any():

r = re.compile('.*search.*')
if any(r.match(line) for line in output):
    do_stuff()

Passing in the lazy generator to any() will allow it to exit on the first match without having to check any farther into the iterable.