Grouping Regular Expression in Python

Question

I'm having a problem. I'm trying to figure out what is the regular expression for the following situation, where I want to match one of the follwoing if returned back.

               ABC 1 or 
               ABC 1 0  or
               ABC 1 0 1  or 
               ABC 1 0 1 0 or etc

I'm trying the following to acheive this but its only matching the first string (ABC 1).

               regular expression: ABC (1|0)+

I have been trying to figure this out for a long time and I can't seem to figure it out. Could someone please help?

Thanks

You may want to include a combination of spaces and 1s and 0s probably? — erewok
– erewok, Commented Sep 19, 2013 at 19:23
ABC( (1|0))+ perhaps? Or ABC( 1 0)*( 1)? if you must have alternating 0's and 1's. — PaulMcG
– PaulMcG, Commented Sep 19, 2013 at 19:28

Jerry · Accepted Answer · 2013-09-19 20:33:03Z

2

If you want to make sure it's first a 1, then a 0, then another 1, then a 0 etc, you might use this:

re.match(r'ABC(?: 1(?: 0|$))+$', s)

regex101 demo

EDIT: If you don't care about the order, you can use this:

re.match(r'ABC(?: [01])+$', s)

edited Sep 19, 2013 at 20:33

answered Sep 19, 2013 at 19:33

Jerry

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2 Comments

user2796819 Over a year ago

Thanks but I dont want to change from 0 to 1. I just have a response where I have a string and numbers.

Jerry Over a year ago

@user2796819 There was someone else who had posted an answer with a regex to match any order, but he deleted his answer and I don't know why :( Anyway, see if the second regex works for you!

Nitzan Shaked · Accepted Answer · 2013-09-19 19:58:05Z

0

ABC1(01)*0?

ABC, then 1, then zero or more 0 1, and finally an optional 0. Assuming you don't want white spaces, of course.

If you want a single space after each "part":

ABC 1( 0 1)*( 0)?

edited Sep 19, 2013 at 19:58

answered Sep 19, 2013 at 19:30

Nitzan Shaked

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1 Comment

Nitzan Shaked Over a year ago

To the downvoters: I believe you are mistaken. The way I understand the question, he wants "ABC" and then a sequence of 1's and 0's, alternating, ending in either a 1 or a 0. I was neglecting whitespace, of course.

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