Polar Scatter Chart

This example demonstrates how to create polar scatter charts. It also demonstrates using alternating background colors along the angular direction.

A polar scatter chart can be created as a polar line chart with data symbols. The line width is set to 0, so only the symbols can be seen. This will create the effects of a scatter chart.

The detail steps are:

Create a polar line layer using PolarChart.addLineLayer.
Enable data symbols for the line using PolarLayer.setDataSymbol (or PolarLayer.setDataSymbol2 or PolarLayer.setDataSymbol3 or PolarLayer.setDataSymbol4).
Disable the line by setting its width to 0 using PolarLayer.setLineWidth.

Note that in this example, the polar plot area uses two alternating background colors along the angular direction. This is by using PolarChart.setPlotAreaBg.

perldemo\polarscatter.pl

#!/usr/bin/perl

# The ChartDirector for Perl module is assumed to be in "../lib"
use File::Basename;
use lib (dirname($0)."/../lib") =~ /(.*)/;

use perlchartdir;

# The data for the chart
my $data0 = [43, 89, 76, 64, 48, 18, 92, 68, 44, 79, 71, 85];
my $angles0 = [45, 96, 169, 258, 15, 30, 330, 260, 60, 75, 110, 140];

my $data1 = [50, 91, 26, 29, 80, 53, 62, 87, 19, 40];
my $angles1 = [230, 210, 240, 310, 179, 250, 244, 199, 89, 160];

my $data2 = [88, 65, 76, 49, 80, 53];
my $angles2 = [340, 310, 340, 210, 30, 300];

# The labels on the angular axis (spokes)
my $labels = ["North", "North\nEast", "East", "South\nEast", "South", "South\nWest", "West",
    "North\nWest"];

# Create a PolarChart object of size 460 x 460 pixels
my $c = new PolarChart(460, 460);

# Add a title to the chart at the top left corner using 15pt Arial Bold Italic font
$c->addTitle2($perlchartdir::TopLeft, "<*underline=2*>Plants in Wonderland", "Arial Bold Italic", 15
    );

# Set center of plot area at (230, 240) with radius 180 pixels
$c->setPlotArea(230, 240, 180);

# Use alternative light grey/dark grey sector background color
$c->setPlotAreaBg(0xdddddd, 0xeeeeee, 0);

# Set the grid style to circular grid
$c->setGridStyle(0);

# Add a legend box at the top right corner of the chart using 9pt Arial Bold font
$c->addLegend(459, 0, 1, "Arial Bold", 9)->setAlignment($perlchartdir::TopRight);

# Set angular axis as 0 - 360, either 8 spokes
$c->angularAxis()->setLinearScale2(0, 360, $labels);

# Set the radial axis label format
$c->radialAxis()->setLabelFormat("{value} km");

# Add a blue (0xff) polar line layer to the chart using (data0, angle0)
my $layer0 = $c->addLineLayer($data0, 0x0000ff, "Immortal Weed");
$layer0->setAngles($angles0);

$layer0->setLineWidth(0);
$layer0->setDataSymbol($perlchartdir::TriangleSymbol, 11);

# Add a red (0xff0000) polar line layer to the chart using (data1, angles1)
my $layer1 = $c->addLineLayer($data1, 0xff0000, "Precious Flower");
$layer1->setAngles($angles1);

# Disable the line by setting its width to 0, so only the symbols are visible
$layer1->setLineWidth(0);

# Use a 11 pixel diamond data point symbol
$layer1->setDataSymbol($perlchartdir::DiamondSymbol, 11);

# Add a green (0x00ff00) polar line layer to the chart using (data2, angles2)
my $layer2 = $c->addLineLayer($data2, 0x00ff00, "Magical Tree");
$layer2->setAngles($angles2);

# Disable the line by setting its width to 0, so only the symbols are visible
$layer2->setLineWidth(0);

# Use a 9 pixel square data point symbol
$layer2->setDataSymbol($perlchartdir::SquareSymbol, 9);

# Output the chart
$c->makeChart("polarscatter.png");