Python regex pattern matching with ranges and whitespaces

Question

I am attempting to match strings that would have a pattern of:

two uppercase Latin letters
two digits
two uppercase Latin letters
four digits
ex: MH 45 LE 4098

There can be optional whitespaces between the first three and they need to be limited to these numbers of characters. I was trying to group them and set a limit on the characters, but I am not matching any strings that fall within the define parameters. I had attempted building a set like so template = '[A-Z{2}0-9{2,4}]', but was still receiving errors when the last digits had exceeded 4.

template = '(A-Z{2})\s?(\d{2})\s?(A-Z{2})\s?(\d{4})'

This was the other attempt when I tried being more verbose, but then couldn't match anything.

No, sorry. I just wrote an example. I should have been clearer in my description. — NotPretendingToBeSomebodyElse, Apr 22 '21 at 06:22

Sufian Latif · Answer 1 · 2021-04-22T15:06:49.577

1

This is probably the regex you are looking for:

[A-Z]{2}\s?[0-9]{2}\s?[A-Z]{2}\s?[0-9]{4}

Note that it allows multiple whitespace characters.

edited Apr 22 '21 at 15:06

answered Apr 22 '21 at 06:12

Sufian Latif

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Would it be better to indicate numbers by `\d` instead of `[0-9]` ? – SeaBean Apr 22 '21 at 06:18
I thought there is no difference, but your comment made me look into this thread: https://stackoverflow.com/questions/16621738/d-less-efficient-than-0-9. Apparently, `\d` would capture any unicode digits. – Sufian Latif Apr 22 '21 at 06:23
Would there be a way to limit the whitespace to one character instead of allowing multiple? – NotPretendingToBeSomebodyElse Apr 22 '21 at 06:31
Just that `\d` looks more succinct and commonly gives cleaner regex especially when the regex is long. – SeaBean Apr 22 '21 at 06:41
@NotPretendingToBeSomebodyElse sure, a `?` instead of a `*` will do the job. Please see the edited answer. – Sufian Latif Apr 22 '21 at 15:07

score 1 · Accepted Answer · answered Apr 22 '21 at 06:12

1

You are close; need to put a square brackets around A-Z to let {2} affect the whole range instead of only Z. As it stands it literally matches A-ZZ.

So

template = "[A-Z]{2}\s?(\d{2})\s?([A-Z]{2})\s?(\d{4})"

should do. We use [ instead of ( to imply a range of letters. If we put (, it would try to match A-ZA-Z i.e. literally A-Z two times.

You can see a demo here and you can change them to ( or omit them to see the effect in the demo.

answered Apr 22 '21 at 06:12

Mustafa Aydın

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That did work! Ah, that makes sense. Thank you for that resource too! I'm going to go check it out now. I appreciate your help. – NotPretendingToBeSomebodyElse Apr 22 '21 at 06:30

Python regex pattern matching with ranges and whitespaces

2 Answers2