Extracting groups in a regex match

Question

I have a set of inputs. I am trying to write a regex to match the following pattern in the input:

Day at Time on location

Example input:

Today at 12:30 PM on Sam's living room

The bolded part of the text varies in each input.

I wrote the following regex:

import regex as re

input_example = "Today at 12:30 PM on Rakesh's Echo"
regexp_1 = re.compile(r'(\w+) at (\d+):(\d+) (\w+) on (\w+)')
re_match = regexp_1.match(input_example)

Which works, I am matching the correct patterns. I am now trying to extract groups from within the pattern.

My desired output is:

re_match.group(1)
>> "Today"
re_match.group(2)
>> "12:30 PM"
re_match.group(3)
>> "Sam's living room"

However, my current regular expression match does not give me this output. What is the correct regex that will give me the above outputs?

Answer 1

You can make nested groups, but in that way it would be not very readable, because you have to compute the exact number of the group and then you will forget what exactly means that number.

It's better to use named groups. This is copied from the REPL:

>>> import re
... 
... input_example = "Today at 12:30 PM on Rakesh's Echo"
... regexp_1 = re.compile(r'(?P<day>\w+) at (?P<time>(\d+):(\d+) (\w+)) on (?P<place>\w+)')
... re_match = regexp_1.match(input_example)
>>> list(re_match.groups())
['Today', '12:30 PM', '12', '30', 'PM', 'Rakesh']
>>> re_match.group('day')
'Today'
>>> re_match.group('time')
'12:30 PM'
>>> re_match.group('place')
'Rakesh'