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I am trying to use Regex to extract title cased phrases and word that occur within the sentences.

Effort so far:

(?:[A-Z][a-z]+\s?)+

This regex code when applied on the sample sentence below finds those words shown as bold. But I need to ignore words like This and Whether (sentence starters).

Sample Sentence:

This is a Sample Sentence to check the Real Value of this code. Whether it works or Not depends upon the result.

Expectation:

This is a Sample Sentence to check the Real Value of this code. Whether it works or Not depends upon the result.

Useful code:

import regex as re

text='This is a Sample Sentence to check the Real Value of this code. Whether it works or Not depends upon the result. A State Of The Art Technology is needed to do this work.'
rex=r'(?<!^|[.!?]\ )\b[A-Z][a-z]+(?:\ [A-Z][a-z]+)*\b'

matches = re.finditer(rex,text)
results = [match[0] for match in matches]
print(results)

Result:

['Sample Sentence', 'Real Value', 'Not', 'State Of The Art Technology']
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2 Answers 2

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3

Assuming your regex flavor supports Lookbehinds, I would use something like this:

(?<!^|\.\ )\b[A-Z][a-z]+(?:\ [A-Z][a-z]+)*\b

Demo.

This will support words that are preceded by an abbreviation, punctuation, or pretty much anything other than a period (end of previous sentence).

Edit:

As per Nick's suggestion in the comments, it's probably better to include ! and ? in the Lookbehind to support sentences ending with either of them, not just the period:

(?<!^|[.!?]\ )\b[A-Z][a-z]+(?:\ [A-Z][a-z]+)*\b

Demo.

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4 Comments

You should probably allow for sentences to end in ? or ! as well.
@Nick It can indeed end with anything. It just won't be included in the match (which is what I believe the OP intended). I think that the OP's pattern including the trailing whitespace was just a side-effect of them trying to include multiple consecutive words in one match.
I was referring to your negative lookbehind, it would be better with [.!?] than \.
@Programmer_nltk you might find this solution more flexible if your sentence structure can include punctuation in the middle of them.
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If your sentence is always single spaced, you can use a positive lookbehind for a letter and a space to find the start of a title-cased expression:

(?<=[a-z,] )(?:[A-Z][a-z]+(?![a-z]).)+

This regex allows for the expression to end in punctuation instead of just a space (e.g. the Final Result.).

Demo on regex101

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2 Comments

This will not match things like Bb in AA Bb or Aa, Bb. Although not included in OP's example, I think they would want to match those as well (I could be wrong thoough).
@AhmedAbdelhameed I'm not sure about AA Bb but Aa, Bb might well be valid. It's a good point.

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