NAME
URI::GoogleChart - Generate Google Chart URIs
SYNOPSIS
use URI::GoogleChart;
my $chart = URI::GoogleChart->new("lines", 300, 100,
data => [45, 80, 55, 68],
range_show => "left",
range_round => 1,
);
# save chart to a file
use LWP::Simple qw(getstore);
getstore($chart, "chart.png");
# or embed chart in an HTML file
use HTML::Entities;
my $enc_chart = encode_entities($chart);
open(my $fh, ">", "chart.html") || die;
print $fh qq(
<h1>My Chart</h1>
<p><img src="$enc_chart"></p>
);
close($fh) || die;
DESCRIPTION
This module provide a constructor method for Google Chart URLs. When
dereferenced Google will serve back PNG images of charts based on the
provided parameters.
The Google Chart service is described at
<http://code.google.com/apis/chart/> and these pages also define the Web
API in terms of the parameters these URLs take. This module make it
easier to generate URLs that conform to this API as it automatically
takes care of data encoding and scaling, as well as hiding most of the
cryptic parameter names that the API uses in order to generate shorter
URLs.
The following constructor method is provided:
$uri = URI::GoogleChart->new( $type, $width, $height, %opt )
The constructor method's first 3 arguments are mandatory and they
define the type of chart to generate and the dimension of the image
in pixels. Additional arguments are provided as key/value pairs. The
return value is an HTTP URI object, which can also be treated as a
string.
The $type argument can either be one of the type code documented at
the Google Charts page or one of the following more readable
aliases:
lines
sparklines
xy-lines
horizontal-stacked-bars
vertical-stacked-bars
horizontal-grouped-bars
vertical-grouped-bars
pie
pie-3d
concentric-pie
venn
scatter-plot
radar
radar-splines
google-o-meter
world
africa
asia
europe
middle_east
south_america
usa
The additional arguments in the form of key/value pairs can either
be one of the "chXXX" parameters documented on the Google Chart
pages or one of the following:
data => [{ v => [$v1, $v2,...], %opt }, ...]
data => [[$v1, $v2,...], [$v1, $v2,...], ...]
data => [$v1, $v2,...]
data => $v1
The data to be charted is provided as an array of data series.
In the most general form each series is defined by a hash with
the "v" element being an array of data points (numbers) in the
series. Missing data points should be provided as "undef". Other
hash elements can be provided to define various properties of
the series. These are described below.
As a short hand when you don't need to define other properties
besides the data points you can provide an array of numbers
instead of the series hash.
As a short hand when you only have a single data series, you can
provide a single array of numbers, and finally if you only have
a single number you can provide it without wrapping it in an
array.
Data series belong to ranges. A range is defined by a minimum
and a maximum value. Data points are scaled so that they are
plotted relative to the range they belong to. For example if the
range is (5 .. 10) then a data point value of 7.5 is plotted in
the middle of the chart area. Ranges are automatically
calculated based on the data provided, but you can also force
certain minimum and maximum values to apply.
The following data series properties can be provided in addition
to "v" described above:
The "range" property can be used to group data series together
that belong to the same range. The value of the "range" property
is a range name. Data series without a "range" property belong
to the default range.
min => $num
max => $num
Defines the default minimum and maximum value for the default
range. If not provided the minimum and maximum is calculated
from the data points belonging to this range.
The specified minimum or maximum are ignored if some of data
values provided are outside this range.
Chart types that plot relative values (like bar charts or venn
diagrams) should use 0 as the minimum, as this make the relative
size of the data points stay the same after scaling. Because of
this the default default minimum for these charts is 0, so you
don't actually need to specify it.
range_round => $bool
Extend the default range so that the min/max values are nice
multiples of 1, 5, 10, 50, 100,... and such numbers. This gives
the chart more "air" and look better if you display the range of
values with "range_show".
range_show => "left"
range_show => "right"
range_show => "top"
range_show => "bottom"
Makes the given axis show the range of values charted for the
default range.
range => { $name => \%opt, ...},
Define parameters for named data series ranges. The range named
"" is the default range.
The option values that can be set are "min", "max", "round",
"show". See the description of the corresponding entry for the
default range above.
encoding => "t"
encoding => "s"
encoding => "e"
Select what kind of data encoding you want to be used. They
differ in the resolution they provide and in their readability
and verbosity. Resolution matters if you generate big charts.
Verbosity matters as some web client might refuse to dereference
URLs that are too long.
The "t" (or "text") encoding is the most readable and verbose.
It might consume up to 5 bytes per data point. It provide a
resolution of 1/1000.
The "s" (or "simple") encoding is the most compact; only
consuming 1 byte per data point. It provide a resolution of
1/62.
The "e" (or "extended") encoding provides the most resolution
and it consumes 2 bytes per data point. It provide a resolution
of 1/4096.
The default encoding is automatically selected based on the
resolution of the chart and the number of data points provided.
color => $color
color => [$color1, $color2, ...]
Sets the colors to use for charting the data series. The
canonical form for $color is hexstrings either of "RRGGBB" or
"RRGGBBAA" form. When you use this interface you might also use
"RGB" form as well as some comon names like "red", "blue",
"green", "white", "black",... which are expanded to the
canonical form in the URL.
The built in colors are the 16 colors of the HTML specification
(see <http://en.wikipedia.org/wiki/HTML_color_names>). If you
want to use additional color names you can assign your mapping
to the %URI::GoogleChart::COLOR_ALIAS hash before start creating
charts. Example:
local $URI::GoogleChart::COLOR_ALIAS{"gold"} = "FFD700";
background => $color
Sets the color for the chart background. See description for
color above for how to specify color values. The color value
"transparent" gives you a fully transparent background.
title => $str
title => [ $str, $color, $fontsize ]
Sets the title for the chart; optionally changing the color and
fontsize used for the title.
label = $str
label = [ $str, $str,... ]
Labels the data (or data series) of the chart.
rotate => $degrees
Rotate the orientation of a pie chart (clockwise).
The first slice starts at the right side of the pie (at 3
o'clock). If you rotate the pie 90 degrees the first slice
starts at the bottom. If you rotate -90 degrees (or 270) the
first slices starts at the top of the pie.
margin => $num
margin => [ $left, $right, $top, $bottom ]
Sets the chart margins in pixels. If a single number is provided
then all the margins are set to this number of pixels.
SEE ALSO
<http://cpansearch.perl.org/src/GAAS/URI-GoogleChart-1.02/examples.html>
<http://code.google.com/apis/chart/>
URI
COPYRIGHT AND LICENSE
Copyright 2009 Gisle Aas.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.