Question

In regular expression in python

[abc] matches either a or b or c

How to do [abc] that matches either ab or bc ? Is this possible ?

Answer 1

Use the | regular expression operator to specify multiple possibilities:

>>> import re
>>> pattern = re.compile("ab|bc")
>>>
>>> print pattern.match("abbbb")
<_sre.SRE_Match object at 0x105117918>
>>> print pattern.match("fooo")
None
>>> print pattern.match("bcdd")
<_sre.SRE_Match object at 0x105117918>
>>> print pattern.match("abc")
<_sre.SRE_Match object at 0x105117918>

Wrap them in brackets if it’s part of a larger expression:

>>> pattern = re.compile("(red|green) light")
>>> print pattern.match("red light")
<_sre.SRE_Match object at 0x105117918>
>>> print pattern.match("red lights everywhere")
<_sre.SRE_Match object at 0x1051116c0>
>>> print pattern.match("green lights forever")
<_sre.SRE_Match object at 0x105117918>
>>> print pattern.match("blue lights begone")
None

See regular expression syntax in the Python documentation for all of the options.