How to fetch names using RegEx for given pattern?

Question

I'm trying to fetch below patterns from the text using RegEx:

John Doe
JOHN DOE
Sam John Watson
Sam John Lilly Watson
SAM JOHN WATSON
SAM JOHN LILLY WATSON

Input Data only contains single line and I need to find above patterns in that.

More about Pattern

Each word will start with a Uppercase letter and followed by either Upper or Lowercase
Minimum 2 words
Maximum 4 words
Words will include only A-Z or a-z chars

What I Tried:

import re
re.findall("[A-Z][A-Za-z]+ [A-Z][A-Za-z]+ [A-Za-z]* [A-Za-z]*", text)

Which will correctly identifies input like:

Sam Peters John Doe
SAM WINCH DAN BROWN

but fails on input with less than 4 words.

If this is for a real system rather than a programming exercise, it is probably worth reading Falsehoods Programmers Believe About Names — user9723177
– user9723177, Commented Dec 27, 2018 at 9:57

CertainPerformance · Accepted Answer · 2018-12-27 10:04:27Z

3

Your pattern is failing because even with the *s after the last two character sets, the spaces next to those last two character sets are not optional. So (for example) having only 2 words in the string would only match if those two words were followed by two spaces.

I'd suggest that you start with [A-Z][A-Za-z]+ for the first word, then repeat a space followed by a word up to 3 times:

^[A-Z][A-Za-z]+(?: [A-Z][A-Za-z]+){1,3}$

https://regex101.com/r/IvSvAH/1

If there may be words with only one character (like "I" or "A"), then repeat the [A-Za-z] character sets with * instead of +.

edited Dec 27, 2018 at 10:04

answered Dec 27, 2018 at 9:52

CertainPerformance

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2 Comments

Sociopath Over a year ago

works like a charm. It would be more helpful if you point out why my solution failed in this case.

Tim Biegeleisen Over a year ago

@Sociopath I might also suggest a new username. But +1 to this answer.

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