Python正则表达式仅在数字匹配时匹配

Question

Given the regex and the word below I want to match the part after the - (which can also be a _ or space) only if the part after the delimiter is a digit and nothing comes after it (I basically want to to be a number and number only). I am using group statements but it just doesn't seem to work right. It keeps matching the 3 at the beginning (or the 1 at the end if I modify it a bit). How do I achieve this (by using grouping) ?

Target word: BR0227-3G1

Regex: ([AZ]*\\s?[0-9]*)[\\s_-]*([1-9][1-9]*)

It should not match 3G1, G1 , 1G

It should match only pure numbers like 3,10, 2 etc.

Here is also a helper web site for evaluating the regex: http://www.pythonregex.com/

More examples:

It should match:

BR0227-3
BR0227 3
BR0227_3

into groups (BR0227) (3)

It should only match (BR0227) for

BR0227-3G1
BR0227-CS
BR0227
BR0227-

Answer 1

I would use

re.findall('^([A-Z]*\s?[0-9]*)[\s_-]*([1-9][1-9]*$)?', str)

Each string starts with the first group and ends with the last group, so the ^ and $ groups can assist in capture. The $ at the end requires all numbers to be captured, but it's optional so the first group can still be captured.

Answer 2

Since you want the start and (possible) end of the word in groups, then do this:

r'\b([A-Z0-9]+)(?:[ _-](\d+))?\b'

This will put the first part of the word in the first group, and optionally the remainder in the second group. The second group will be None if it didn't match.

Answer 3

该名称应与后跟“-”，“”或“ _”且后面仅数字的任何内容匹配。

(.*)[- _](\d+)