Wrap timecode into brackets using regular expression

user_1918919 0
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In a string, I need all timecodes to be formatted as following [HH:MM:SS] or [HH:MM:SS.ms]. Some of them are already in brackets. They can be everywhere, beginning, middle, or end of a phrase.

I'd like to put those not in brackets in brackets.

To select all of them I use:

[\[]?\d\d:\d\d:\d\d(.\d+)?[\]]?

I tried

(?!\[.+\])(.|^)(\d\d:\d\d:\d\d(.\d+)?)(.|$)(?!\[.+\])

Which is almost fine except that my selection $2 includes space characters in the case of string not beggining by ^ or finishing by $.

How can I get rid of this selection?

python regex
1 Answers

You can use

re.sub(r'\[?\b(\d{2}:\d{2}:\d{2}(?:\.\d+)?)\b]?', r'[\1]', text)

See the regex demo. Details:

  • \[? - an optional [ char
  • \b - a word boundary
  • (\d{2}:\d{2}:\d{2}(?:\.\d+)?) - Group 1:
    • \d{2}:\d{2}:\d{2} - two digits, and then two occurrences of : and two digits
    • (?:\.\d+)? - an optional sequence of . and one or more digits
  • \b - a word boundary
  • ]? - an optional ] char

To make sure you match 24-hour time format you can use a more precise pattern:

\[?\b((?:[01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9](?:\.[0-9]+)?)\b]?

See this demo.

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