Cache historical values
use Cache::Historical;
my $cache = Cache::Historical->new();
# Set a key's value on a specific date
$cache->set( $dt, $key, $value );
# Get a key's value on a specific date
my $value = $cache->get( $dt, $key );
# Same as 'get', but if we don't have a value at $dt, but we
# do have values for dates < $dt, return the previous
# historic value.
$cache->get_interpolated( $dt, $key );
Cache::Historical caches historical values by key and date. If you have something like historical stock quotes, for example
2008-01-02 msft 35.22 2008-01-03 msft 35.37 2008-01-04 msft 34.38 2008-01-07 msft 34.61
then you can store them in Cache::Historical like
my $cache = Cache::Historical->new();
my $fmt = DateTime::Format::Strptime->new( pattern => "%Y-%m-%d");
$cache->set( $fmt->parse_datetime("2008-01-02"), "msft", 35.22 ); $cache->set( $fmt->parse_datetime("2008-01-03"), "msft", 35.37 ); $cache->set( $fmt->parse_datetime("2008-01-04"), "msft", 34.38 ); $cache->set( $fmt->parse_datetime("2008-01-07"), "msft", 34.61 );
and retrieve them later by date:
my $dt = $fmt->parse_datetime("2008-01-03");
# Returns 35.37 my $value = $cache->get( $dt, "msft" );
Even if there's no value available for a given date, but there are historical values that predate the requested date, \*(C`get_interpolated()\*(C' will return the next best historical value:
my $dt = $fmt->parse_datetime("2008-01-06");
# Returns undef, no value available for 2008-01-06 my $value = $cache->get( $dt, "msft" );
# Returns 34.48, the value for 2008-01-04, instead. $value = $cache->get_interpolated( $dt, "msft" );
Creates the object. Takes the SQLite file to put the date into as an additional parameter: my $cache = Cache::Historical->new( sqlite_file => "/tmp/mydata.dat", ); The SQLite file defaults to $HOME/.cache-historical/cache-historical.dat so if you have multiple caches, you need to use different SQLite files.
# List the time range for which we have values for $key my($from, $to) = $cache->time_range( $key );
# List all keys my @keys = $cache->keys();
# List all the values we have for $key, sorted by date # ([$dt, $value], [$dt, $value], ...) my @results = $cache->values( $key );
# Remove all values for a specific key $cache->clear( $key );
# Clear the entire cache $cache->clear();
# Return a DateTime object of the last update of a given key my $when = $cache->last_update( $key );
# Return a DateTime::Duration object since the time of the last # update of a given key. my $since = $cache->since_last_update( $key );
Copyright 2007-2011 by Mike Schilli, all rights reserved. This program is free software, you can redistribute it and/or modify it under the same terms as Perl itself.
2007, Mike Schilli <[email protected]>