207 – Regex groups with default values

A regex match has the method groups that returns a tuple with all of the groups that the pattern contained:

import re

pattern = r"""(?x)
    (\d+)  # 1 or more digits
    \.?    # An optional .
    (\d+)? # More optional digits
"""

m = re.match(pattern, "24.5")

print(m.groups())
# ('24', '5')

However, if one or more of the groups did not participate in the match, it will be replaced with the default value None:

m = re.match(pattern, "24")

print(m.groups())
# ('24', None)

Alternatively, you can provide your own value for the groups that didn’t participate:

print(m.groups("0"))
# ('24', '0')