NAME

       Algorithm::HyperLogLog - Implementation of the HyperLogLog cardinality estimation
       algorithm

SYNOPSIS

         use Algorithm::HyperLogLog;

         my $hll = Algorithm::HyperLogLog->new(14);

         while(<>){
             $hll->add($_);
         }

         my $cardinality = $hll->estimate(); # Estimate cardinality
         $hll->dump_to_file('hll_register.dump');# Dumps internal data

       Construct object from dumped file.

         use Algorithm::HyperLogLog;

         # Restore internal state
         my $hll = Algorithm::HyperLogLog->new_from_file('hll_register.dump');

DESCRIPTION

       This module is implementation of the HyperLogLog algorithm.

       HyperLogLog is an algorithm for estimating the cardinality of a set.

METHODS

   new($b)
       Constructor.

       `$b` is the parameter for determining register size. (The register size is 2^$b.)

       `$b` must be a integer between 4 and 16.

   new_from_file($filename)
       This method constructs object and restore the internal data of object from dumped
       file(dumped by dump_to_file() method).

   dump_to_file($filename)
       This method dumps the internal data of an object to a file.

   add($data)
       Adds element to the cardinality estimator.

   estimate()
       Returns estimated cardinality value in floating point number.

   merge($other)
       Merges the estimate from 'other' into this object, returning the estimate of their union.

   register_size()
       Return number of register.(In the XS implementation, this equals size in bytes)

   XS()
       If using XS backend, this method return true value.

SEE ALSO

       Philippe Flajolet, Éric Fusy, Olivier Gandouet and Frédéric Meunier. HyperLogLog: the
       analysis of a near-optimal cardinality estimation algorithm. 2007 Conference on Analysis
       of Algorithms, DMTCS proc. AH, pp. 127–146, 2007.
       <http://algo.inria.fr/flajolet/Publications/FlFuGaMe07.pdf>

AUTHOR

       Hideaki Ohno <hide.o.j55 {at} gmail.com>

THANKS TO

       MurmurHash3(<https://github.com/PeterScott/murmur3>)

       Austin Appleby
       Peter Scott

LICENSE

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