Hi Monks.
I'm trying to learn Bayesian programming, and have found this code. It seems to work fine, but I'd like to be able to see what words it has associated for each category after it has run. Unfortunatly the Hash has me totally confused and I don't know how to print out the words in each category. Can anyone help me with a function to do this?

use strict;
use DB_File;

# Hash with two levels of keys: $words{category}{word} gives count of
# 'word' in 'category'.  Tied to a DB_File to keep it persistent.

my %words;
tie %words, 'DB_File', 'words.db';

# Read a file and return a hash of the word counts in that file

sub parse_file
{
    my ( $file ) = @_;
    my %word_counts;

    # Grab all the words with between 3 and 44 letters

    open FILE, "<$file";
    while ( my $line = <FILE> ) {
        while ( $line =~ s/([[:alpha:]]{3,44})[ \t\n\r]// ) {
            $word_counts{lc($1)}++;
        }
    }
    close FILE;
    return %word_counts;
}

# Add words from a hash to the word counts for a category
sub add_words
{
    my ( $category, %words_in_file ) = @_;

    foreach my $word (keys %words_in_file) {
        $words{"$category-$word"} += $words_in_file{$word};
    }
}

# Get the classification of a file from word counts
sub classify
{
    my ( %words_in_file ) = @_;

    # Calculate the total number of words in each category and
    # the total number of words overall

    my %count;
    my $total = 0;
    foreach my $entry (keys %words) {
        $entry =~ /^(.+)-(.+)$/;
        $count{$1} += $words{$entry};
        $total += $words{$entry};
    }

    # Run through words and calculate the probability for each categor
+y

    my %score;
    foreach my $word (keys %words_in_file) {
        foreach my $category (keys %count) {
            if ( defined( $words{"$category-$word"} ) ) {
                $score{$category} += log( $words{"$category-$word"} /
                                          $count{$category} );
            } else {
                $score{$category} += log( 0.01 /
                                          $count{$category} );
            }
        }
    }
    # Add in the probability that the text is of a specific category

    foreach my $category (keys %count) {
        $score{$category} += log( $count{$category} / $total );
    }
    foreach my $category (sort { $score{$b} <=> $score{$a} } keys %cou
+nt) {
        print "$category $score{$category}\n";
    }
}

# Supported commands are 'add' to add words to a category and
# 'classify' to get the classification of a file

if ( ( $ARGV[0] eq 'add' ) && ( $#ARGV == 2 ) ) {
    add_words( $ARGV[1], parse_file( $ARGV[2] ) );
} elsif ( ( $ARGV[0] eq 'classify' ) && ( $#ARGV == 1 ) ) {
    classify( parse_file( $ARGV[1] ) );
} else {
    print <<EOUSAGE;
Usage: add <category> <file> - Adds words from <file> to category <cat
+egory>
       classify <file>       - Outputs classification of <file>
EOUSAGE
}

untie %words;
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