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How can I print out a word-frequency or line-frequency summary?

by faq_monk (Initiate)
on Oct 08, 1999 at 00:25 UTC ( #669=perlfaq nodetype: print w/replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

To do this, you have to parse out each word in the input stream. We'll pretend that by word you mean chunk of alphabetics, hyphens, or apostrophes, rather than the non-whitespace chunk idea of a word given in the previous question:

    while (<>) {
        while ( /(\b[^\W_\d][\w'-]+\b)/g ) {   # misses "`sheep'"
            $seen{$1}++;
        }
    }
    while ( ($word, $count) = each %seen ) {
        print "$count $word\n";
    }

If you wanted to do the same thing for lines, you wouldn't need a regular expression:

    while (<>) { 
        $seen{$_}++;
    }
    while ( ($line, $count) = each %seen ) {
        print "$count $line";
    }

If you want these output in a sorted order, see the section on Hashes.

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choroba waves is
[choroba]: 'Tyrol' =~ tr/Ty o/Pe/rd
choroba hates the CB and its space insertion
Eily wondered if the space was there for a reason
[Eily]: like "Replace the T, replace the y, skip one, replace the o"
[Discipulus]: it works anyway, good morning choroba

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