正则表达式匹配数字组后跟或不跟空格，单词

Question

I'm trying to match with regex:

101.6 x 101.6 mm
150   x      150 mm
490 x 100 x 380 mm
490 x 100 x 380 x 430 mm
280mm x 260 mm

and extract the value(digits) as separate groups. I'm using:

^(?P<value>[-\.\d]+)([\s]*)([x]+) 

but, I want something that doesn't care about how many times the digits appear.

What I want to obtain as groups:

101.6, 101.6, mm
150, 150, mm
490, 100, 380, mm
490, 100, 380, 430, mm
280, 260, mm

I know, can be done with split as it is, but besides the examples above, I have also other expressions that contains "x" and in there case I don't want to split.

Answer 1

Given that all the strings in the example data end with mm and mm might also optionally occur after a digit, you could match an optional occurrence and use a positive lookahead to assert that the string also ends with mm and that what comes in between are to only allowed parts.

If you want to match multiple spaces, you could use [ ]+ with the brackets in this case for clarity. If there can be more kinds of whitspaces except a newline you could use [^\S\r\n]* instead.

Based on multiple spaces, you might use

\b(?P<value>\d+(?:\.\d+)?)(?: *mm)?(?=(?: +x +\d+(?:\.\d+)?)* mm\b)

Regex demo | Python demo

For example

import re

regex = r"\b(?P<value>\d+(?:\.\d+)?)(?: *mm)?(?=(?: +x +\d+(?:\.\d+)?)* mm\b)"

test_str = ("101.6 x 101.6 mm\n"
    "150   x      150 mm\n"
    "490 x 100 x 380 mm\n"
    "490 x 100 x 380 x 430 mm\n"
    "280mm x 260 mm")

print(re.findall(regex, test_str))

Output

['101.6', '101.6', '150', '150', '490', '100', '380', '490', '100', '380', '430', '280', '260']