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.
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.
