NAME

Geo::Hash::XS - Geo::Hash in XS

SYNOPSIS

            

              
              
my $gh = Geo::Hash::XS->new();
my $hash = $gh->encode( $lat, $lon );  # default precision = 32
my $hash = $gh->encode( $lat, $lon, $precision ); 
my ($lat, $lon) = $gh->decode( $hash );
            
          

DESCRIPTION

Geo::Hash::XS encodes and decodes geohash strings, fast.

Currently this module is alpha quality (especially the adjacent() and negihbors() methods, which I just kind of copied the logic from elsewhere). Please submit tests and patches!

METHODS

$gh = Geo::Hash::XS->new()

$hash = $gh->encode($lat, $lon[, $precision])

Encodes the given $lat and $lon to a geohash. If $precision is not given, automatically adjusts the precision according the the given $lat and $lon values.

If you do not want Geo::Hash::XS to spend time calculating this, explicitly specify $precision.

($lat, $lon) = $gh->decode( $hash )

Decodes $hash to $lat and $lon

($lat_range, $lon_range) = $gh->decode_to_interval( $hash )

Like decode() but decode_to_interval() decodes $hash to $lat_range and $lon_range. Each range is a reference to two element arrays which contains the upper and lower bounds.

$adjacent_hash = $gh->adjacent($hash, $where)

Returns the adjacent geohash. $where denotes the direction, so if you want the block to the right of $hash, you say:

            

              
              
use Geo::Hash::XS qw(ADJ_RIGHT);
my $gh = Geo::Hash::XS->new();
my $adjacent = $gh->adjacent( $hash, ADJ_RIGHT );
            
          

@list_of_geohashes = $gh->neighbors($hash, $around, $offset)

Returns the list of neighbors (the blocks surrounding $hash)

$precision = $gh->precision($lat, $lon)

Returns the apparent required precision to describe the given latitude and longitude.

CONSTANTS

ADJ_LEFT, ADJ_RIGHT, ADJ_TOP, ADJ_BOTTOM

Used to specify the direction in adjacent()

PERFORMANCE

Here's the output from running benchmark/encode.pl:

            

              
              
Geo::Hash: 0.02
Geo::Hash::XS: 0.00014
precision = auto...
         Rate  perl    xs
perl  18332/s    --  -98%
xs   964744/s 5163%    --
precision = 5...
          Rate  perl    xs
perl   16500/s    --  -98%
xs   1011557/s 6030%    --
precision = 10...
         Rate   perl     xs
perl   8650/s     --   -99%
xs   980236/s 11232%     --
precision = 20...
         Rate   perl     xs
perl   4736/s     --   -99%
xs   858875/s 18035%     --
precision = 30...
         Rate   perl     xs
perl   3050/s     --  -100%
xs   712136/s 23252%     --
            
          

Obviously, the benefit of doing this calculation in XS becomes larger with higher precision, but generaly you don't need precision > 10.

LICENSE

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

See http://www.perl.com/perl/misc/Artistic.html

AUTHOR

Copyright (c) 2010 Daisuke Maki <daisuke@endeworks.jp>

cpanm Geo::Hash::XS

perl -MCPAN -e shell
install Geo::Hash::XS