Regex from python list

Question

Today, I found out that regex r"['a', 'b']" matches 'a, b'.

Why is that? What does comma and ' mean inside []?

Thank you.

Have you tried reading the documentation docs.python.org/2/library/re.html ? — Tom Dalton
– Tom Dalton, Commented Nov 7, 2016 at 15:39
Possible duplicate of Reference - What does this regex mean? — coder
– coder, Commented Nov 7, 2016 at 15:53

TheF1rstPancake · Accepted Answer · 2016-11-07 15:54:35Z

2

[] is used to define character sets in regular expressions. The expression will match if the string contains any of the characters in that set.

Your regular expression:

 r"['a', 'b']"

Says "match if string contains ' or a or , or b. As @Patrick Haugh mentions in his comment. Your expression is equivalent to [',ab]. Repeating the same character in the set does nothing.

http://www.regexpal.com/ is a great site for testing your regular expressions. It can help break it down for you and explain what your expression does and why it matches on certain strings.

answered Nov 7, 2016 at 15:54

TheF1rstPancake

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