Calculate the Jaccard Similarity Coefficient.

# NAME

Set::Jaccard::SimilarityCoefficient - Calculate the Jaccard Similarity Coefficient of 2 sets

# VERSION

# SYNOPSIS

\$res = Set::Jaccard::SimilarityCoefficient::calc(\@set_a, \@set_b);

OR

my \$a = Set::Scalar->new(@set_a); my \$b = Set::Scalar->new(@set_b); \$res = Set::Jaccard::SimilarityCoefficient::calc(\$a, \$b);

# DESCRIPTION

Set::Jaccard::SimilarityCoefficient lets you calculate the Jaccard Similarity Coefficient for either arrayrefs or Set::Scalar objects.

Briefly, the Jaccard Similarity Coefficient is a simple measure of how similar 2 sets are. The calculation is (in pseudo-code):

``    count(difference(SET-A, SET-B)) / count(union(SET-A, SET-B))``

There is a Jaccard Similarity Coefficient routine already in CPAN, but it is specialized for use by Text::NSP. I wanted a generic routine that could be used by anyone so Set::Jaccard::SimilarityCoefficient was born.

# SUBROUTINES/METHODS

calc(A, B) calculates the Jaccard Similarity Coefficient for the arguments A and B. A and B can be either array references or Set::Scalar objects.

# DIAGNOSTICS

new() will complain if A or B is empty, not either a reference to an array, or not a Set::Scalar object.

calc() could theoretically throw DivideByZeroException when the union of the two sets has 0 members. However, that would require set A or set B to have 0 members, which was previously prohibited by the prohibition on empty sets.

# CONFIGURATION AND ENVIRONMENT

This module should work wherever Perl works.

Set::Scalar

# INCOMPATIBILITIES

None that I know of.

# BUGS AND LIMITATIONS

There are no bugs that I know of. Given that this is non-trivial code, there will be bugs.

The types of arguments are limited to either array references or Set::Scalar objects.

# AUTHOR

Mark Leighton Fisher, <markleightonfisher@gmail.com>