Find out how many times a regex matches in a string in Python

Question

Is there a way that I can find out how many matches of a regex are in a string in Python? For example, if I have the string \"It actually happened when it acted out of

Answer 1

To avoid creating a list of matches one may also use re.sub with a callable as replacement. It will be called on each match, incrementing internal counter.

class Counter(object):
    def __init__(self):
        self.matched = 0
    def __call__(self, matchobj):
        self.matched += 1

counter = Counter()
re.sub(some_pattern, counter, text)

print counter.matched