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>>> match = re.findall(r'\w\w', 'hello') >>> print match ['he', 'll'] Since \w\w means two characters, 'he' and 'll' are expected. But why do 'el' and 'lo' not match the regex?
>>> match1 = re.findall(r'el', 'hello') >>> print match1 ['el'] >>> 
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You can use the new Python regex module, which supports overlapping matches.
The method str. match(regexp) finds matches for regexp in the string str . If the regexp has flag g , then it returns an array of all matches as strings, without capturing groups and other details. If there are no matches, no matter if there's flag g or not, null is returned.
This will return an array of all non-overlapping regex matches in the string. “Non-overlapping” means that the string is searched through from left to right, and the next match attempt starts beyond the previous match.
A regex pattern matches a target string. The pattern is composed of a sequence of atoms. An atom is a single point within the regex pattern which it tries to match to the target string. The simplest atom is a literal, but grouping parts of the pattern to match an atom will require using ( ) as metacharacters.
findall doesn't yield overlapping matches by default. This expression does however:
>>> re.findall(r'(?=(\w\w))', 'hello') ['he', 'el', 'll', 'lo'] Here (?=...) is a lookahead assertion:
(?=...)matches if...matches next, but doesn’t consume any of the string. This is called a lookahead assertion. For example,Isaac (?=Asimov)will match'Isaac 'only if it’s followed by'Asimov'.
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You can use the new Python regex module, which supports overlapping matches.
>>> import regex as re >>> match = re.findall(r'\w\w', 'hello', overlapped=True) >>> print match ['he', 'el', 'll', 'lo'] If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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