ChartDirector Ver 5.0 (PHP Edition)

Bubble Chart

This example demonstrates how to create a bubble chart.
In ChartDirector, a bubble chart can be created as a scatter layer with circles as symbols using XYChart.addScatterLayer. The sizes of the symbols are then controlled by another data series (z data) using LineLayer.setSymbolScale. This creates circles of different sizes.
By default, ChartDirector handles z data using pixel units. That means a z value of 50 will result in a symbol size of 50 pixels. If your z data are too small or too large, you may re-scale them using ArrayMath.mul before passing them to LineLayer.setSymbolScale.
ChartDirector also supports handling the z data using the same scale as the y (or x) axis by supplying additional arguments to LineLayer.setSymbolScale. This is useful if the symbol sizes reflect some features of the y (or x) data, such as the standard deviation or confidence of the y (or x) value.

Source Code Listing

[File: phpdemo/bubble.php]

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

    # The XYZ points for the bubble chart
    $dataX0 = array(150, 300, 1000, 1700);
    $dataY0 = array(12, 60, 25, 65);
    $dataZ0 = array(20, 50, 50, 85);

    $dataX1 = array(500, 1000, 1300);
    $dataY1 = array(35, 50, 75);
    $dataZ1 = array(30, 55, 95);

    # Create a XYChart object of size 450 x 420 pixels
    $c = new XYChart(450, 420);

    # Set the plotarea at (55, 65) and of size 350 x 300 pixels, with a light grey border
    # (0xc0c0c0). Turn on both horizontal and vertical grid lines with light grey color
    # (0xc0c0c0)
    $c->setPlotArea(55, 65, 350, 300, -1, -1, 0xc0c0c0, 0xc0c0c0, -1);

    # Add a legend box at (50, 30) (top of the chart) with horizontal layout. Use 12 pts
    # Times Bold Italic font. Set the background and border color to Transparent.
    $legendObj = $c->addLegend(50, 30, false, "timesbi.ttf", 12);
    $legendObj->setBackground(Transparent);

    # Add a title to the chart using 18 pts Times Bold Itatic font.
    $c->addTitle("Product Comparison Chart", "timesbi.ttf", 18);

    # Add a title to the y axis using 12 pts Arial Bold Italic font
    $c->yAxis->setTitle("Capacity (tons)", "arialbi.ttf", 12);

    # Add a title to the x axis using 12 pts Arial Bold Italic font
    $c->xAxis->setTitle("Range (miles)", "arialbi.ttf", 12);

    # Set the axes line width to 3 pixels
    $c->xAxis->setWidth(3);
    $c->yAxis->setWidth(3);

    # Add (dataX0, dataY0) as a scatter layer with semi-transparent red (0x80ff3333)
    # circle symbols, where the circle size is modulated by dataZ0. This creates a bubble
    # effect.
    $scatterLayerObj = $c->addScatterLayer($dataX0, $dataY0, "Technology AAA",
        CircleSymbol, 9, 0x80ff3333, 0x80ff3333);
    $scatterLayerObj->setSymbolScale($dataZ0);

    # Add (dataX1, dataY1) as a scatter layer with semi-transparent green (0x803333ff)
    # circle symbols, where the circle size is modulated by dataZ1. This creates a bubble
    # effect.
    $scatterLayerObj = $c->addScatterLayer($dataX1, $dataY1, "Technology BBB",
        CircleSymbol, 9, 0x803333ff, 0x803333ff);
    $scatterLayerObj->setSymbolScale($dataZ1);

    # Output the chart
    header("Content-type: image/png");
    print($c->makeChart2(PNG));
    ?>

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