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.

[File: phpdemo/polarscatter.php]

<?php
require_once("../lib/phpchartdir.php");

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

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

$data2 = array(88, 65, 76, 49, 80, 53);
$angles2 = array(340, 310, 340, 210, 30, 300);

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

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

# Add a title to the chart at the top left corner using 15pt Arial Bold Italic font
$c->addTitle2(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, false);

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

# Add a legend box at the top right corner of the chart using 9pt Arial Bold font
$c->addLegend(459, 0, true, "Arial Bold", 9)->setAlignment(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)
$layer0 = $c->addLineLayer($data0, 0x0000ff, "Immortal Weed");
$layer0->setAngles($angles0);

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

# Add a red (0xff0000) polar line layer to the chart using (data1, angles1)
$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(DiamondSymbol, 11);

# Add a green (0x00ff00) polar line layer to the chart using (data2, angles2)
$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(SquareSymbol, 9);

# Output the chart
$viewer = new WebChartViewer("chart1");
$viewer->setChart($c, SVG);

# Include tool tip for the chart
$viewer->setImageMap($c->getHTMLImageMap("", "",
    "title='{dataSetName} at ({value} km, {angle} deg)'"));
?>

<!DOCTYPE html>
<html>
<head>
    <title>Polar Scatter Chart</title>
    <!-- Include ChartDirector Javascript Library to support chart interactions -->
    <script type="text/javascript" src="cdjcv.js"></script>
</head>
<body style="margin:5px 0px 0px 5px">
    <div style="font:bold 18pt verdana;">
        Polar Scatter Chart
    </div>
    <hr style="border:solid 1px #000080; background:#000080" />
    <div style="font:10pt verdana; margin-bottom:1.5em">
        <a href="viewsource.php?file=<?=basename(__FILE__)?>">View Chart Source Code</a>
    </div>
    <!-- ****** Here is the chart image ****** -->
    <?php echo $viewer->renderHTML(); ?>
</body>
</html>