NAME

    Set::Similarity - similarity measures for sets

SYNOPSIS

     use Set::Similarity::Dice;
     
     # object method
     my $dice = Set::Similarity::Dice->new;
     my $similarity = $dice->similarity('Photographer','Fotograf');
     
     # class method
     my $dice = 'Set::Similarity::Dice';
     my $similarity = $dice->similarity('Photographer','Fotograf');
     
     # from 2-grams
     my $width = 2;
     my $similarity = $dice->similarity('Photographer','Fotograf',$width);
     
     # from arrayref of tokens
     my $similarity = $dice->similarity(['a','b'],['b']);
    
     # from hashref of features 
     my $bird = {
       wings    => true,
       eyes     => true,
       feathers => true,
       hairs    => false,
       legs     => true,
       arms     => false,
     };
     my $mammal = {
       wings    => false,
       eyes     => true,
       feathers => false,
       hairs    => true,
       legs     => true,
       arms     => true, 
     };
     my $similarity = $dice->similarity($bird,$mammal);
     
     # from arrayref sets
     my $bird = [qw(
       wings
       eyes
       feathers
       legs
     )];
     my $mammal = [qw(
       eyes
       hairs
       legs
       arms
     )];
     my $similarity = $dice->from_sets($bird,$mammal);

DESCRIPTION

    This is the base class including mainly helper and convenience methods.

 Overlap coefficient

    ( A intersect B ) / min(A,B)

 Jaccard Index

    The Jaccard coefficient measures similarity between sample sets, and is
    defined as the size of the intersection divided by the size of the
    union of the sample sets

    ( A intersect B ) / (A union B)

    The Tanimoto coefficient is the ratio of the number of features common
    to both sets to the total number of features, i.e.

    ( A intersect B ) / ( A + B - ( A intersect B ) ) # the same as Jaccard

    The range is 0 to 1 inclusive.

 Dice coefficient

    The Dice coefficient is the number of features in common to both sets
    relative to the average size of the total number of features present,
    i.e.

    ( A intersect B ) / 0.5 ( A + B ) # the same as sorensen

    The weighting factor comes from the 0.5 in the denominator. The range
    is 0 to 1.

METHODS

    All methods can be used as class or object methods.

 new

      $object = Set::Similarity->new();

 similarity

      my $similarity = $object->similarity($any1,$any1,$width);
      

    $any can be an arrayref, a hashref or a string. Strings are tokenized
    into n-grams of width $width.

    $width must be integer, or defaults to 1.

 from_tokens

      my $similarity = $object->from_tokens(['a','b'],['b']);

 from_sets

      my $similarity = $object->from_sets(['a'],['b']);
      

    Croaks if called directly. This method should be implemented in a child
    module.

 intersection

      my $intersection_size = $object->intersection(['a'],['b']);
      

 uniq

      my @uniq = $object->uniq(['a','b']);
      

    Transforms an arrayref of strings into an array of unique elements.

 combined_length

      my $set_size_sum = $object->combined_length(['a'],['b']);

 min

      my $min_set_size = $object->min(['a'],['b']);
      

 ngrams

      my @monograms = $object->ngrams('abc');
      my @bigrams = $object->ngrams('abc',2);

 _any

      my $arrayref = $object->_any($any,$width);
      

SEE ALSO

    Set::Similarity::Cosine

    Set::Similarity::Dice

    Set::Similarity::Jaccard

    Set::Similarity::Overlap

    Bag::Similarity doing the same for bags or multisets.

    Text::Levenshtein for distance measures of strings, and a very overview
    of similar modules,

    http://en.wikipedia.org/wiki/String_metric for an overview of
    similarity measures.

    Cluster::Similarity for clusters.

SOURCE REPOSITORY

    http://github.com/wollmers/Set-Similarity

AUTHOR

    Helmut Wollmersdorfer, <helmut.wollmersdorfer@gmail.com>

COPYRIGHT AND LICENSE

    Copyright (C) 2013-2015 by Helmut Wollmersdorfer

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.