lookahead and lookbehind regex not matching

Asked Jan 12 '21 at 22:01

Active Jan 12 '21 at 22:03

Viewed 23 times

I have been trying to get some regex statements to work for the past few hours, but I can not seem to figure out what I am doing wrong.

here is what I currently have:

(?<!.)\d{4}[\.]\d{2}(?!.)|(?<!.)\d{4}(?!.)

The data I am trying to match looks like

but it is mixed into other text and numbers. I need to filter out anything with preceding or proceeding characters so it does not match something like the following

d12394-005

edited Jan 12 '21 at 22:03

The fourth bird

154,723
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asked Jan 12 '21 at 22:01

Anthony Brinkhuis

1

Use `re.findall(r'\b(?<!\.)\d{4}(?:\.\d{2})?\b(?!\.)', text)` ([demo](https://regex101.com/r/Au82kN/1)) – Wiktor Stribiżew Jan 12 '21 at 22:04
@WiktorStribiżew That is it, you could consider making a post out of it. – The fourth bird Jan 12 '21 at 22:07
It would help if you provided a [mre], including some example input and your Python code. BTW, welcome to SO! Check out the [tour], and [ask] if you want tips. – wjandrea Jan 12 '21 at 22:08
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@Thefourthbird On second thought, OP simply wants word boundaries. `re.findall(r'\b\d{4}(?:\.\d{2})?\b', text)`. – Wiktor Stribiżew Jan 12 '21 at 22:09
Word boundaries, makes sense. Thanks everyone! – Anthony Brinkhuis Jan 13 '21 at 00:16

lookahead and lookbehind regex not matching

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