Re: regex issue
by AnomalousMonk (Archbishop) on Aug 03, 2016 at 19:03 UTC
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First of all, I don't understand if you want all three-letter immediately repeated words, as your OPed regex
/\b(\w\w\w)\s\g1\b/;/
implies, or all three-letter words that are repeated anywhere else in the string, as your code implies.
In the spirit of the second interpretation (and counting them) (requires Perl version 5.10+ for \g-1 construct):
c:\@Work\Perl>perl -wMstrict -MData::Dump -le
"use 5.010;
;;
my $term = 'Dit is het eerste het is xhetx xhet hetx niet het laatste
+ Dit';
;;
my $word = qr{ \b \w{3} \b }xms;
;;
my %repeats;
while ($term =~ m{ ($word) (?= .*? (?= $word) \g-1) }xmsg) {
$repeats{$1}++;
}
;;
dd \%repeats;
"
{ Dit => 1, het => 2 }
Change the definition of $word to whatever best suits your requirements. | See Update 3 below.
Updates:
- Added info about 5.10+ requirement.
- BTW, the "regex" /\b(\w\w\w)\s\g1\b/;/ doesn't actually compile. It looks like it might be a piece of something else, e.g., a substitution:
s/\b(\w\w\w)\s\g1\b/;/
(update: or maybe the / at the end is completely extraneous and the statement /\b(\w\w\w)\s\g1\b/; was intended — that would work)
-
When I wrote "Change the definition of $word to whatever best suits your requirements" above, what I had in mind was that any $word definition used in the context of the
m{ ($word) (?= .*? (?= $word) \g-1) }xmsg
match would be assured to match repeated words per my understanding of the OP. Not so, and it's easy to manufacture a counterexample. Of course, it's also easy to fix the counterexample to avoid the problem, but the fix requires knowledge of internal details of the $word definition, and this is exactly what I was trying to avoid. In a further iteration, I can come up with a match regex that seems to fulfill all my (admittedly rather arbitrary) requirements, but it's not well tested and I don't really love it as I should. So as always, Caveat Programmor.
Give a man a fish: <%-{-{-{-<
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Why are you using ';;' every blank line? If you want a blank line, leave a blank line. If you want a comment, use the perl comment character, '#'.
As Occam said: Entia non sunt multiplicanda praeter necessitatem.
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What you're seeing is a perl -e " ... code ... " Windose command line padded out with spaces to emulate the appearance of multi-line source. The code comes from the Windoze clipboard. The original intent was to quickly cut/paste, possibly modify, and test posted code snippets, so I decided to eliminate blank lines. If I want to have something that looks like a blank line, "something" has to be there, and by convention, I use ;; as that something.
By the same token, because what's after the -e switch is just a single string/line, any # comment-to-end-of-line just clobbers the entire remainder of the line, even though the remainder appears multi-line. So, no comments.
Give a man a fish: <%-{-{-{-<
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Re: regex issue
by Laurent_R (Canon) on Aug 03, 2016 at 19:14 UTC
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use strict;
use warnings;
my $term = 'Dit is het eerste het is niet het laatste Dit';
my @tlw = $term =~ /\b(\w{3})\b/g;
# Now you have all the three-letter words, so count them
my %seen = ();
$seen{$_}++ for @tlw;
for my $k (keys %seen) {
print "$k occurs $seen{$k} times\n" if $seen{$k} > 1;
}
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Re: regex issue
by Anonymous Monk on Aug 03, 2016 at 16:49 UTC
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$term = 'Dit is het eerste het is niet het laatste Dit';
@captured = $term =~ /\b(\w\w\w)\b(?=.*\1\b)/g;
print join ' ', @captured;
_____________
Dit het het
The \b are word boudaries (change from letter/number/underscore) to non-letter/number/underscore or vice-versa.
The (?= looks forward for what comes after it, but remembers where it starts.
The \1 is the same as your \g1 (I unfortunately have an older perl.)
The g at the end means capture them all
het appears twice since it is there three times | [reply] [d/l] |
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Small correction, you missed a word-boundary assertion in the look-ahead. The regex should be:
/\b(\w\w\w)\b(?=.*\b\1\b)/g
Without the additional \b before \1, three-letter words that are trailing substrings of other words would also match. | [reply] [d/l] |
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