graph(3)

NAME

GD::Graph - Graph Plotting Module for Perl 5

SYNOPSIS

use GD::Graph::moduleName;

DESCRIPTION

GD::Graph is a perl5 module to create charts using the GD module. The following classes for graphs with axes are
defined:

"GD::Graph::lines": Create a line chart.
"GD::Graph::bars" and "GD::Graph::hbars": Create a bar chart with vertical or horizontal bars.
"GD::Graph::points": Create an chart, displaying the data as points.
"GD::Graph::linespoints": Combination of lines and points.
"GD::Graph::area": Create a graph, representing the data as areas under a
line.
"GD::Graph::mixed": Create a mixed type graph, any combination of the
above. At the moment this is fairly limited. Some of
the options that can be used with some of the individ
ual graph types won't work very well. Multiple bar
graphs in a mixed graph won't display very nicely.
Additional types:
"GD::Graph::pie": Create a pie chart.

EXAMPLES

See the samples directory in the distribution, and read
the Makefile there.

USAGE

Fill an array of arrays with the x values and the values of the data sets. Make sure that every array is the same size, otherwise GD::Graph will complain and refuse to com pile the graph.: @data = (
["1st","2nd","3rd","4th","5th","6th","7th", "8th",

"9th"],
[ 1, 2, 5, 6, 3, 1.5, 1, 3,

4],
[ sort { $a <=> $b } (1, 2, 5, 6, 3, 1.5, 1, 3, 4) ]; );
If you don't have a value for a point in a certain
dataset, you can use undef, and the point will be skipped.
Create a new GD::Graph object by calling the new method on the graph type you want to create (chart is bars, lines, points, linespoints, mixed or pie).: $graph = GD::Graph::chart->new(400, 300);
Set the graph options.: $graph->set(
x_label => 'X Label',
y_label => 'Y label',
title => 'Some simple graph',
y_max_value => 8,
y_tick_number => 8,
y_label_skip => 2; );
and plot the graph.: my $gd = $my_graph->plot(@data);
Then do whatever your current version of GD allows you to do to save the file. For versions of GD older than 1.19, you'd do something like:: open(IMG, '>file.gif') or die $!;
binmode IMG;
print IMG $gd->gif;
close IMG;
and for newer versions (1.20 and up) you'd write: open(IMG, '>file.png') or die $!;
binmode IMG;
print IMG $gd->png;
or: open(IMG, '>file.gd2') or die $!;
binmode IMG;
print IMG $gd->gd2;
Then there's also of course the possibility of using a shorter version (for each of the export functions that GD supports):: print IMG $my_graph->plot(@data)->gif;
print IMG $my_graph->plot(@data)->png;
print IMG $my_graph->plot(@data)->gd;
print IMG $my_graph->plot(@data)->gd2;
If you want to write something that doesn't require your code to 'know' whether to use gif or png, you could do something like:: if ($gd->can('png')) { # blabla }
or you can use the convenience method "export_format":: my $format = $my_graph->export_format;
open(IMG, ">file.$format") or die $!;
binmode IMG;
print IMG $my_graph->plot(@data)->$format();
close IMG;
or for CGI scripts:: use CGI qw(:standard);
#...
my $format = $my_graph->export_format;
print header("image/$format");
binmode STDOUT;
print $my_graph->plot(@data)->$format();
(the parentheses after $format are necessary, to help the compiler decide that you mean a method name there)

METHODS

Methods for all graphs

GD::Graph::chart->new([width,height]): Create a new object $graph with optional width and
heigth. Default width = 400, default height = 300.
chart is either bars, lines, points, linespoints, area, mixed or pie.
$graph->set_text_clr(colour name): Set the colour of the text. This will set the colour
of the titles, labels, and axis labels to colour name. Also see the options textclr, labelclr and axislabel_ clr.
$graph->set_title_font(font specification): Set the font that will be used for the title of the
chart. See "FONTS".
$graph->plot(_@data): Plot the chart, and return the GD::Image object.
$graph->set(attrib1 => value1, attrib2 => value2 ...): Set chart options. See OPTIONS section.
$graph->get(attrib1, attrib2): Returns a list of the values of the attributes. In
scalar context returns the value of the first
attribute only.
$graph->gd(): Get the GD::Image object that is going to be used to
draw on. You can do this either before or after call
ing the plot method, to do your own drawing.; Note that if you draw on the GD::Image object before
calling the plot method that you are responsible for
making sure that the background colour is correct and
for setting transparency.
$graph->export_format(): Query the export format of the GD library in use. In
scalar context, it returns 'gif', 'png' or undefined,
which is sufficient for most people's use. In a list
context, it returns a list of all the formats that are
supported by the current version of GD. It can be
called as a class or object method
$graph->can_do_ttf(): Returns true if the current GD library supports True
Type fonts, False otherwise. Can also be called as a
class method or static method.
Methods for Pie charts
$graph->set_label_font(font specification) $graph->set_value_font(font specification): Set the font that will be used for the label of the
pie or the values on the pie. See "FONTS".
Methods for charts with axes.
$graph->set_x_label_font(font specification) $graph->set_y_label_font(font specification) $graph->set_x_axis_font(font specification) $graph->set_y_axis_font(font specification) $graph->set_values_font(font specification): Set the font for the x and y axis label, the x and y
axis value labels, and for the values printed above
the data points. See "FONTS".
$graph->get_hotspot($dataset, $point): Experimental: Return a coordinate specification for a point in a dataset. Returns a list. If the point is
not specified, returns a list of array references for
all points in the dataset. If the dataset is also not
specified, returns a list of array references for each
data set. See "HOTSPOTS".

OPTIONS

Options for all graphs

width, height: The width and height of the canvas in pixels Default:
400 x 300. NB At the moment, these are read-only
options. If you want to set the size of a graph, you
will have to do that with the new method.
t_margin, b_margin, l_margin, r_margin: Top, bottom, left and right margin of the canvas.
These margins will be left blank. Default: 0 for all.
logo: Name of a logo file. Generally, this should be the
same format as your version of GD exports images in.
At the moment there is no support for reading gd for
mat files or xpm files. Default: no logo.
logo_resize, logo_position: Factor to resize the logo by, and the position on the
canvas of the logo. Possible values for logo_position
are 'LL', 'LR', 'UL', and 'UR'. (lower and upper left
and right). Default: 'LR'.
transparent: If set to a true value, the produced image will have
the background colour marked as transparent (see also
option bgclr). Default: 1.
interlaced: If set to a true value, the produced image will be
interlaced. Default: 1.
Colours
bgclr, fgclr, boxclr, accentclr, shadowclr: Drawing colours used for the chart: background, fore
ground (axes and grid), axis box fill colour, accents
(bar, area and pie outlines), and shadow (currently
only for bars).; All colours should have a valid value as described in
"COLOURS", except boxclr, which can be undefined, in
which case the box will not be filled.
shadow_depth: Depth of a shadow, positive for right/down shadow,
negative for left/up shadow, 0 for no shadow
(default). Also see the "shadowclr" and "bar_spacing"
options.
labelclr, axislabelclr, legendclr, valuesclr, textclr: Text Colours used for the chart: label (labels for the
axes or pie), axis label (misnomer: values printed
along the axes, or on a pie slice), legend text, shown
values text, and all other text.; All colours should have a valid value as described in
"COLOURS".
dclrs (short for datacolours): This controls the colours for the bars, lines, mark
ers, or pie slices. This should be a reference to an
array of colour names as defined in GD::Graph::colour
("perldoc GD::Graph::colour" for the names available).

$graph->set( dclrs => [ qw(green pink blue cyan) ]

);; The first (fifth, ninth) data set will be green, the
next pink, etc.; A colour can be "undef", in which case the data set
will not be drawn. This can be useful for cumulative
bar sets where you want certain data series (often the
first one) not to show up, which can be used to emu
late error bars (see examples 1-7 and 6-3 in the dis
tribution). Default: [ qw(lred lgreen lblue lyellow
lpurple cyan lorange) ]
borderclrs: This controls the colours of the borders of the bars
data sets. Like dclrs, it is a reference to an array
of colour names as defined in GD::Graph::colour. Set
ting a border colour to "undef" means the border will
not be drawn.
cycle_clrs: If set to a true value, bars will not have a colour
from "dclrs" per dataset, but per point. The colour
sequence will be identical for each dataset. Note that
this may have a weird effect if you are drawing more
than one data set. If this is set to a value larger
than 1 the border colour of the bars will cycle
through the colours in "borderclrs".
accent_treshold: Not really a colour, but it does control a visual
aspect: Accents on bars are only drawn when the width
of a bar is larger than this number of pixels. Accents
inside areas are only drawn when the horizontal dis
tance between points is larger than this number.
Default 4
Options for graphs with axes.
options for bars, lines, points, linespoints, mixed and area charts.
x_label, y_label: The labels to be printed next to, or just below, the
axes. Note that if you use the two_axes option that
you need to use y1_label and y2_label.
long_ticks, tick_length: If long_ticks is a true value, ticks will be drawn the same length as the axes. Otherwise ticks will be
drawn with length tick_length. if tick_length is nega tive, the ticks will be drawn outside the axes.
Default: long_ticks = 0, tick_length = 4.; These attributes can also be set for x and y axes sep
arately with x_long_ticks, y_long_ticks, x_tick_length
and y_tick_length.
x_ticks: If x_ticks is a true value, ticks will be drawm for
the x axis. These ticks are subject to the values of
long_ticks and tick_length. Default: 1.
y_tick_number: Number of ticks to print for the Y axis. Use this,
together with y_label_skip to control the look of ticks on the y axis. Default: 5.
y_number_format: This can be either a string, or a reference to a sub
routine. If it is a string, it will be taken to be the
first argument to an sprintf, with the value as the
second argument:

$label = sprintf( $s->{y_number_format}, $value );; If it is a code reference, it will be executed with
the value as the argument:

$label = &{$s->{y_number_format}}($value);; This can be useful, for example, if you want to refor
mat your values in currency, with the - sign in the
right spot. Something like:

sub y_format
{
my $value = shift;
my $ret;

if ($value >= 0)
{
$ret = sprintf("d", $value * $refit);

}
else
{

$ret = sprintf("-d", abs($value) * $re

fit);

}

return $ret;

}

$my_graph->set( 'y_number_format' => y_format );; (Yes, I know this can be much shorter and more con
cise); Default: undef.
x_label_skip, y_label_skip: Print every x_label_skipth number under the tick on the x axis, and every y_label_skipth number next to the tick on the y axis. Default: 1 for both.
x_tick_offset: When x_label_skip is used, this will skip the first
x_tick_offset values in the labels before starting to
print. Let me give an example. If you have a series of
X labels like

qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec); and you set x_label_skip to 3, you will see ticks on
the X axis for Jan, Apr, Jul, Oct and Dec. This is not
always what is wanted. If you set x_tick_offset to 1,
you get Feb, May, Aug, Nov and Dec, and if you set it
to 2, you get Mar, Jun Sep and Dec, and this last one
definitely looks better. A combination of 6 and 5 also
works nice for months.; Note that the value for x_tick_offset is periodical.
This means that it will have the same effect for each
nteger n in x_tick_offset + n * x_label_skip.
x_all_ticks: Force a print of all the x ticks, even if x_label_skip
is set to a value Default: 0.
x_label_position: Controls the position of the X axis label (title). The
value for this should be between 0 and 1, where 0
means aligned to the left, 1 means aligned to the
right, and 1/2 means centered. Default: 3/4
y_label_position: Controls the position of both Y axis labels (titles).
The value for this should be between 0 and 1, where 0
means aligned to the bottom, 1 means aligned to the
top, and 1/2 means centered. Default: 1/2
x_labels_vertical: If set to a true value, the X axis labels will be
printed vertically. This can be handy in case these
labels get very long. Default: 0.
x_plot_values, y_plot_values: If set to a true value, the values of the ticks on the
x or y axes will be plotted next to the tick. Also see
x_label_skip, y_label_skip. Default: 1 for both.
box_axis: Draw the axes as a box, if true. Default: 1.
two_axes: Use two separate axes for the first and second data
set. The first data set will be set against the left
axis, the second against the right axis. If this is
set to a true value, trying to use anything else than
2 datasets will generate an error.; Note that if you use this option, that you need to use
y1_label and y2_label, instead of just y_label, if you
want the two axes to have different labels. The same
goes for some other options starting with the letter
'y' and an underscore.; Default: 0.
zero_axis: If set to a true value, the axis for y values of 0
will always be drawn. This might be useful in case
your graph contains negative values, but you want it
to be clear where the zero value is. (see also
zero_axis_only and box_axes). Default: 0.
zero_axis_only: If set to a true value, the zero axis will be drawn
(see zero_axis), and no axis at the bottom of the graph will be drawn. The labels for X values will be
placed on the zero exis. Default: 0.
y_max_value, y_min_value: Maximum and minimum value displayed on the y axis. If
two_axes is a true value, then y1_min_value,
y1_max_value (for the left axis), and y2_min_value,
y2_max_value (for the right axis) take precedence over
these.; The range (y_min_value..y_max_value) has to include
all the values of the data points, or GD::Graph will die with a message.; For bar and area graphs, the range
(y_min_value..y_max_value) has to include 0. If it
doesn't, the values will be adapted before attempting
to draw the graph.; Default: Computed from data sets.
axis_space: This space will be left blank between the axes and the
tick value text. Default: 4.
text_space: This space will be left open between text elements and
the graph (text elements are title and axis labels.; Default: 8.
cumulate: If this attribute is set to a true value, the data
sets will be cumulated. This means that they will be
stacked on top of each other. A side effect of this is
that "overwrite" will be set to a true value.; Notes: This only works for bar and area charts at the
moment.; If you have negative values in your data sets, setting
this option might produce odd results. Of course, the
graph itself would be quite meaningless.
overwrite: If set to 0, bars of different data sets will be drawn
next to each other. If set to 1, they will be drawn in
front of each other. Default: 0.; Note: Setting overwrite to 2 to produce cumulative
sets is deprecated, and may disappear in future ver
sions of GD::Graph. Instead see the "cumulate"
attribute.
correct_width: If this is set to a true value and "x_tick_number" is
false, then the width of the graph (or the height for
rotated graphs like "GD::Graph::hbar") will be recal
culated to make sure that each data point is exactly
an integer number of pixels wide. You probably never
want to fiddle with this.; When this value is true, you will need to make sure
that the number of data points is smaller than the
number of pixels in the plotting area of the chart. If
you get errors saying that your horizontal size if too
small, you may need to manually switch this off, or
consider using something else than a bar type for your
chart.; Default: 1 for bar, calculated at runtime for mixed
charts, 0 for others.
Plotting data point values with the data point
Sometimes you will want to plot the value of a data point or bar above the data point for clarity. GD::Graph allows you to control this in a generic manner, or even down to the single point.
show_values: Set this to 1 to display the value of each data point
above the point or bar itself. No effort is being made
to ensure that there is enough space for the text.; Set this to a GD::Graph::Data object, or an array ref
erence of the same shape, with the same dimensions as
your data object that you pass in to the plot method.
The reason for this option is that it allows you to
make a copy of your data set, and selectively set
points to "undef" to disable plotting of them.

my $data = GD::Graph::Data->new(
[ [ 'A', 'B', 'C' ], [ 1, 2, 3 ], [ 11, 12, 13 ]

]);

my $values = $data->copy;
$values->set_y(1, 1, undef);
$values->set_y(2, 0, undef);

$graph->set(show_values => $values);
$graph->plot($data);; Default: 0.
values_vertical: If set to a true value, the values will be printed
vertically, instead of horizontally. This can be handy
if the values are long numbers. Default: 0.
values_space: Space to insert between the data point and the value
to print. Default: 4.
values_format: How to format the values for display. See y_num
ber_format for more information. Default: undef.
Options for graphs with a numerical X axis
First of all: GD::Graph does not support numerical x axis
the way it should. Data for X axes should be equally
spaced. That understood: There is some support to make the
printing of graphs with numerical X axis values a bit bet
ter, thanks to Scott Prahl. If the option "x_tick_number"
is set to a defined value, GD::Graph will attempt to treat
the X data as numerical.
Extra options are:
x_tick_number: If set to 'auto', GD::Graph will attempt to format the X axis in a nice way, based on the actual X values. If
set to a number, that's the number of ticks you will
get. If set to undef, GD::Graph will treat X data as
labels. Default: undef.
x_min_value, x_max_value: The minimum and maximum value to use for the X axis.
Default: computed.
x_number_format: See y_number_format
x_label_skip: See y_label_skip
Options for graphs with bars
bar_width: The width of a bar in pixels. Also see "bar_spacing".
Use "bar_width" If you want to have fixed-width bars,
no matter how wide the chart gets. Default: as wide
as possible, within the constraints of the chart size
and "bar_spacing" setting.
bar_spacing: Number of pixels to leave open between bars. This
works well in most cases, but on some platforms, a
value of 1 will be rounded off to 0. Use "bar_spac
ing" to get a fixed amount of space between bars, with
variable bar widths, depending on the width of the
chart. Note that if "bar_width" is also set, this
setting will be ignored, and automatically calculated.
Default: 0
Options for graphs with lines
line_types: Which line types to use for lines and linespoints graphs. This should be a reference to an array of num
bers:

$graph->set( line_types => [3, 2, 4] );; Available line types are 1: solid, 2: dashed, 3: dot
ted, 4: dot-dashed.; Default: [1] (always use solid)
line_type_scale: Controls the length of the dashes in the line types.
default: 6.
line_width: The width of the line used in lines and linespoints graphs, in pixels. Default: 1.
skip_undef: For all other axes graph types, the default behaviour
is (by their nature) to not draw a point when the Y
value is "undef". For line charts the point gets
skipped as well, but the line is drawn between the
points n-1 to n+1 directly. If "skip_undef" has a true
value, there will be a gap in the chart where a Y
value is undefined.; Note that a line will not be drawn unless there are at
least two consecutive data points exist that have a defined value. The following data set will only plot a
very short line towards the end if "skip_undef" is
set:

@data = (
[ qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct ) ],
[ 1, undef, 2, undef, 3, undef, 4, undef, 5, 6 ]

);; This option is useful when you have a consecutive gap
in your data, or with linespoints charts. If you have
data where you have intermittent gaps, be careful when
you use this. Default value: 0
Options for graphs with points
markers: This controls the order of markers in points and line_ spoints graphs. This should be a reference to an
array of numbers:

$graph->set( markers => [3, 5, 6] );; Available markers are: 1: filled square, 2: open
square, 3: horizontal cross, 4: diagonal cross, 5:
filled diamond, 6: open diamond, 7: filled circle, 8:
open circle, 9: horizontal line, 10: vertical line.
Note that the last two are not part of the default
list.; Default: [1,2,3,4,5,6,7,8]
marker_size: The size of the markers used in points and linespoints graphs, in pixels. Default: 4.
Options for mixed graphs
types: A reference to an array with graph types, in the same
order as the data sets. Possible values are:

$graph->set( types => [qw(lines bars points area

linespoints)] );
$graph->set( types => ['lines', undef, undef,

'bars'] );; values that are undefined or unknown will be set to
"default_type".; Default: all set to "default_type"
default_type: The type of graph to draw for data sets that either
have no type set, or that have an unknown type set.; Default: lines
Graph legends (axestype graphs only)
At the moment legend support is minimal.
Methods
$graph->set_legend(@legend_keys);: Sets the keys for the legend. The elements of @leg
end_keys correspond to the data sets as provided to
plot().; If a key is undef or an empty string, the legend entry
will be skipped.
$graph->set_legend_font(font name);: Sets the font for the legend text (see "FONTS").
Default: GD::gdTinyFont.
Options
legend_placement: Where to put the legend. This should be a two letter
key of the form: 'B[LCR]|R[TCB]'. The first letter
indicates the placement (Bottom or Right), and the
second letter the alignment (Left, Right, Center, Top,
or Bottom). Default: 'BC'; If the legend is placed at the bottom, some calcula
tions will be made to ensure that there is some
'intelligent' wrapping going on. if the legend is
placed at the right, all entries will be placed below
each other.
legend_spacing: The number of pixels to place around a legend item,
and between a legend 'marker' and the text. Default:
4
legend_marker_width, legend_marker_height: The width and height of a legend 'marker' in pixels.
Defaults: 12, 8
lg_cols: If you, for some reason, need to force the legend at
the bottom to have a specific number of columns, you
can use this. Default: computed
Options for pie graphs
3d If set to a true value, the pie chart will be drawn: with a 3d look. Default: 1.
pie_height: The thickness of the pie when 3d is true. Default:
0.1 x height.
start_angle: The angle at which the first data slice will be dis
played, with 0 degrees being "6 o'clock". Default: 0.
suppress_angle: If a pie slice is smaller than this angle (in
degrees), a label will not be drawn on it. Default: 0.
label: Print this label below the pie. Default: undef.

COLOURS

All references to colours in the options for this module
have been shortened to clr. The main reason for this was
that I didn't want to support two spellings for the same
word ('colour' and 'color')

Wherever a colour is required, a colour name should be
used from the package GD::Graph::colour. "perl
doc GD::Graph::colour" should give you the documentation
for that module, containing all valid colour names. I will
probably change this to read the systems rgb.txt file if
it is available.

FONTS

Depending on your version of GD, this accepts both GD
builtin fonts or the name of a TrueType font file. In the
case of a TrueType font, you must specify the font size.
See GD::Text for more details and other things, since all
font handling in GD::Graph is delegated to there.

Examples:: $my_graph->set_title_font('/fonts/arial.ttf', 18);
$my_graph->set_legend_font(gdTinyFont);
$my_graph->set_legend_font(
['verdana', 'arial', gdMediumBoldFont], 12)
(The above discussion is based on GD::Text 0.65. Older versions have more restrictive behaviour).

HOTSPOTS

Note that this is an experimental feature, and its inter_ face may, and likely will, change in the future

GD::Graph keeps an internal set of coordinates for each data point. This specification is very similar to the HTML image map specification, and in fact exists mainly for that purpose. You can get at these hotspots with the "get_hotspot" method. This method accepts two optional arguments, the number of the dataset you're interested in, and the number of the point in that dataset you're inter ested in. When called with two arguments, the method returns a list of one of the following forms:: 'rect', x1, y1, x2, y2
'poly', x1, y1, x2, y2, x3, y3, ....
'line', xs, ys, xe, ye, width
The parameters for "rect" are the coordinates of the cor ners of the rectangle, the parameters for "poly" are the coordinates of the vertices of the polygon, and the param eters for the "line" are the coordinates for the start and end point, and the line width. It should be possible to almost directly translate these lists into HTML image map specifications.
If the second argument to "get_hotspot" is omitted, a list of references to arrays will be returned. This list repre sents all the points in the dataset specified, and each array referred to is of the form outlined above.: ['rect', x1, y1, x2, y2 ], ['rect', x1, y1, x2, y2], ...
if both arguments to "get_hotspot" are omitted, the list that comes back will contain references to arrays for each data set, which in turn contain references to arrays for each point.: [
['rect', x1, y1, x2, y2 ], ['rect', x1, y1, x2, y2],

...; ],
[
['line', xs, ys, xe, ye, w], ['line', xs, ys, xe, ye,

w], ...; ],...

NOTES

As with all Modules for Perl: Please stick to using the
interface. If you try to fiddle too much with knowledge of
the internals of this module, you could get burned. I may
change them at any time.

BUGS

GD::Graph objects cannot be reused. To create a new plot,
you have to create a new GD::Graph object.

Rotated charts (ones with the X axis on the left) can cur
rently only be created for bars. With a little work, this
will work for all others as well. Please, be patient :)

AUTHOR

Martien Verbruggen <mgjv@tradingpost.com.au>

Copyright

Acknowledgements

Thanks to Steve Bonds for releasing Chart::PNGgraph, and
keeping the code alive when GD reached version 1.20, and I
didn't have time to do something about it.

Thanks to the following people for contributing code, or
sending me fixes: Dave Belcher, Steve Bonds, Mike Brem
ford, Damon Brodie, Gary Deschaines brian d foy, Edwin
Hildebrand, Ari Jolma, Tim Meadowcroft, Honza Pazdziora,
Scott Prahl, Vegard Vesterheim, Jeremy Wadsack.

And some people whose real name I don't know, and whose
email address I'd rather not publicise without their con
sent.

docs.sk

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