Regular Expressions 101

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"
(([a-z]*[.:]*)\s*((\d*[.]\d*)+$))
"
igm
1st Capturing Group
(([a-z]*[.:]*)\s*((\d*[.]\d*)+$))
2nd Capturing Group
([a-z]*[.:]*)
Match a single character present in the list below
[a-z]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case insensitive)
Match a single character present in the list below
[.:]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
.:
matches a single character in the list .: (case insensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v  ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
3rd Capturing Group
((\d*[.]\d*)+$)
4th Capturing Group
(\d*[.]\d*)+
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
\d
matches a digit (equivalent to [0-9])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[.]
. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
\d
matches a digit (equivalent to [0-9])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
$ asserts position at the end of a line
Global pattern flags
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
igm

Test String