带有点的Python re.sub（）

Question

I would like to put a space before and after a dot in text but only if its not a part of a date. So far I have this, and i figured out I have to do something with \\D. but it gives back the letter before the dot not only the dot:

string = re.sub("\.", " . ", string)

For example:

Input text: 1992.01.04 is my birthday.

Required output: 1992.01.04 is my birthday .

there is a space before the end of string dot.

Other question is the same with colon and time,

Input text: The time is 11:48, reported by: Tom.

Required output: The time is 11:48, reported by : Tom.

there is a space after text 'reported by' before the colon

Thanks in advance

Answer 1

You can use this regex which does a negative look ahead and negative look behind to check if dot/colon is surrounded by digits and replace it with ' \\1 '

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

Demo, https://regex101.com/r/hr6slz/4

This regex works for both colon and dot and as you can replace it by ' \\1 '

Answer 2

You need _ positive lookbehind assertion._ (or negative, with \\d ). Look into https://docs.python.org/3/library/re.html for details.

re.sub("(?<=\D)\.(\D?)", " . ", '1992.01.04 is my birthday.')