Perl matching multiple capitalized words - regex

Question

I'm doing a perl program (script?) that reads through a text file and identifies all names and categorizes them as either person, location, organization, or miscellaneous. I'm having trouble with things like New York or Pacific First Financial Corp. where there are multiple capitalized words in a row. I've been using:
/([A-Z][a-z]+)+/
to capture as many capitalized words in a row as there are on a given line. From what I understand the + will match 1 or more instances of such pattern, but it's only matching one (i.e. New in New York). For New York, I can just repeate the [A-Z][a-z]+ twice but it doesn't find patterns with more than 2 capitalized words in a row. What am I doing wrong?
PS Sorry if my use of vocabulary is off I'm always so bad with that.

Answer 1

You were just missing the spacing between words.
The following matches whitespace before each word, except the first, so covers the cases you've described:
use strict;
use warnings;
while (<DATA>) {
while (/(?=\w)((?:\s*[A-Z][a-z]+)+)/g) {
print "$1\n";
}
}
__DATA__
I'm doing a perl program (script?) that reads through a text file and identifies all names and categorizes them as either person, location, organization, or miscellaneous. I'm having trouble with things like New York or Pacific First Financial Corp. where there are multiple capitalized words in a row. I've been using:
to capture as many capitalized words in a row as there are on a given line. From what I understand the + will match 1 or more instances of such pattern, but it's only matching one (i.e. New in New York). For New York, I can just repeate the [A-Z][a-z]+ twice but it doesn't find patterns with more than 2 capitalized words in a row. What am I doing wrong?
PS Sorry if my use of vocabulary is off I'm always so bad with that.
Outputs:
New York
Pacific First Financial Corp
From
New
New York
For New York
What
Sorry

Answer 2

There's a CPAN module called Lingua::EN::NamedEntity which seems to do what you want. Might be worth taking a quick look at it.

Answer 3

The How
The pattern you provide, /([A-Z][a-z]+)+/, in your question matches one of more capitalised words given consecutively, like this
This
ThisAndThat
but it won't match this
Not This
It actually matches each of these individually
Not
This
So lets modify the regex to /(?:[A-Z][a-z]+)(?:\s*[A-Z][a-z]+)*/. Now that is a bit of a mouthful so lets break it down a bit at a time
(?: ... ) Groups like this don't capture which is more efficient
[A-Z][a-z]+ Matches a capitalised word
\s*[A-Z][a-z]+ Matches a subsequent capitalised word, optionally starting with
whitespace
The What - TL;DR
Put this all together and we now have a regex that matches a capitalised word, then any subsequent ones with or without whitespace seperation. So it matches
This
ThisAndThat
Not This
We can now abstract this regex a bit to avoid repetition and use it in code as so
my $CAPS_WORD = qr/[A-Z][a-z]+/;
my $FULL_RE = qr/(?:$CAPS_WORD)(?:\s*$CAPS_WORD)*/;
$string =~ /$FULL_RE/;
say $&;
The Why
This answer gives an alternative to the already great one given by #Miller, both will work fine but this solution is quite a bit faster since it doesn't use a lookahead. This is faster than this by a factor of 7
$ time ./bench-simple.pl
Running 100000 runs
800000 matches
real 0m2.869s
user 0m2.860s
sys 0m0.008s
$ time ./bench-lookahead.pl
Running 100000 runs
800000 matches
real 0m19.845s
user 0m19.831s
sys 0m0.012s