python regex skipping optional words not working

Question

I have been trying to find matches where they may be optional words in the string that need to be ignored if they are present.

The code I tried is:

    import re
    str = '''
         topping consensus estimates 
         topping analysis' consensus estimate
         topping estimate
    '''
    for m in re.finditer(r'(?P<p3c>topping\s+(?:\w+\s(?!estimate)){0,2}(estimate))',str):
        print(m.group())
    print('done')

I want to get all three cases found in the string but only get the last. I want to skip up to two words between topping and estimate but cannot guarantee that they will be analysis and consensus. I tried with (?:\w+\s(?!estimate)){0,2} to skip up to two word to get the results but it is not working for some reason.

What is "not working"? Please be more specific.

l'L'l
– l'L'l

2017-12-22 06:29:31 +00:00
Commented Dec 22, 2017 at 6:29 — l'L'l
– l'L'l, Commented Dec 22, 2017 at 6:29

Sweeper · Accepted Answer · 2017-12-22 06:35:17Z

4

You don't need to get "topping estimate" as the result. What you really want is to check whether each line starts with topping followed by 2 or fewer words, then estimate or estimates.

This regex will help you:

^topping(\s\S+){0,2}\sestimates?\s*$

Match this against each line, or multiple lines if you turn on m. It will tell you whether the string satisfies the requirement.

answered Dec 22, 2017 at 6:35

Sweeper

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5 Comments

Pat Over a year ago

Thanks, I needed to modify your suggestion to fit my needs but you have the right approach. I am using just r'topping(\s\S+){0,2}\sestimate' since I do not know where they will be in the text.

Sweeper Over a year ago

@Pat If you think my answer answers your question, please consider accepting it by clicking on that checkmark!

Sweeper Over a year ago

@Pat Define "no longer works". What are you trying to match? What do you expect it to match? What actually matched?

Sweeper Over a year ago

@Pat Try using search instead of findall

Pat Over a year ago

I don't know what happened, but I restarted from scratch and compile is now working!!! Not sure what the problem was but it seems to be gone. Thanks again Sweeper for your help.

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