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 floation point number.

register_size()

Return number of register.(In the XS impelementation, 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.

cpanm Algorithm::HyperLogLog

perl -MCPAN -e shell
install Algorithm::HyperLogLog