How can I plot a time series graph with Perl?

Question

I have some data from a database (SQLite), mapping a value (an integer) to a date. A date is a string with this format: YYYY-MM-DD hh:mm. The dates are not uniformly distributed. I want do draw a line graph with the dates on X and the values on Y. What is the easiest way to do this with Perl?

I tried DBIx::Chart but I could not make it recognize my dates. I also tried GD::Graph, but as the documentation says:

GD::Graph does not support numerical x axis the way it should. Data for X axes should be equally spaced

Answer 1

I tried DBIx::Chart but I could not make it recognize my dates.

Have you tried to translate your dates to Unix-Timestamps and use them as X dates?

Answer 2

The easiest way I've found to do this with Perl is to use the Perl to run a gnuplot process. You can use set timefmt x "%Y-%m-%d" and it will automatically parse the data in the format you have. Gnuplot also supports a variety of output formats.

Answer 3

I would recommend normalizing the dates to integers. The brute force way would be of course using epoch seconds, but that might not look too nice on a graph, so normalize by a linear transform into some decent range (I can provide details of how if you wish).

Answer 4

You can drive gnuplot using Chart::Gnuplot.

Alternatively, if SVG is an acceptable output format, there is SVG::TT::Graph.

Answer 5

You can use Chart::Clicker's Axis::DateTime:

#!/usr/local/bin/perl -w
use strict;
use Chart::Clicker;
use Chart::Clicker::Axis::DateTime;
use Chart::Clicker::Data::Series;
use Chart::Clicker::Data::DataSet;
use Chart::Clicker::Renderer::Point;

my $cc = Chart::Clicker->new;
my $series = Chart::Clicker::Data::Series->new(
    values    => [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ],
    keys      => [
        1256147117, 1256148117, 1256149117, 1256150117, 1256151117, 1256152117,
        1256153117, 1256154117, 1256155117, 1256156117
    ],
);
my $ctx = $cc->get_context('default');
$ctx->domain_axis(Chart::Clicker::Axis::DateTime->new(position => 'bottom', orientation     => 'horizontal'));
my $ds = Chart::Clicker::Data::DataSet->new(series => [ $series ]);
$cc->add_to_datasets($ds);
$cc->write_output('foo.png');

You have to convert your times into Unix timestamps, but it DWIMs.

Answer 6

Do you need your graph to be generated in real time, or is for a one-off report? If the latter, then you can use DateTime modules to generate Excel values and graph them in Excel (or its open-source counterpart.)

use DateTime::Format::MySQL;
use DateTime::Format::Excel;

my $dt = DateTime::Format::MySQL->parse_datetime( '2003-01-16 23:12:01' );
print $dt, "\n";
my $daynum = DateTime::Format::Excel->format_datetime($dt);
print $daynum, "\n";

Time ago I did something like this using Asymptote. It is an incredible package, but it's not easy to use.

Answer 7

Hi, I want to include date in X axes. I have that :

@hours = (
1272672000, 1272758400, 1272844800, 1272931200, 1273017600, 1273104000, 1273208400, 1273294800
);
@bw1 = (
$d1, $d2, $d3, $d4, $d5, $d6, $d7, $d8
);


my $series = Chart::Clicker::Data::Series->new(
    keys => \@hours,
    values => \@bw1,

But on my graphics I don't have the date, but just the day(1,2,3..) How can i have something that 2010-05-12 09:21:21 on my axes X. Thank for your answers. And sorry for my bad english i'm french. Thomas