ChartDirector 7.0 (C++ Edition)

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:

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

Source Code Listing

[The following code is available in "cppdemo/polarscatter". A MFC version of the code is available in "mfcdemo/mfcdemo" (Windows edition only). A QT version of the code is available in "qtdemo/qtdemo".]
#include "chartdir.h"

int main(int argc, char *argv[])
{
    // The data for the chart
    double data0[] = {43, 89, 76, 64, 48, 18, 92, 68, 44, 79, 71, 85};
    const int data0_size = (int)(sizeof(data0)/sizeof(*data0));
    double angles0[] = {45, 96, 169, 258, 15, 30, 330, 260, 60, 75, 110, 140};
    const int angles0_size = (int)(sizeof(angles0)/sizeof(*angles0));

    double data1[] = {50, 91, 26, 29, 80, 53, 62, 87, 19, 40};
    const int data1_size = (int)(sizeof(data1)/sizeof(*data1));
    double angles1[] = {230, 210, 240, 310, 179, 250, 244, 199, 89, 160};
    const int angles1_size = (int)(sizeof(angles1)/sizeof(*angles1));

    double data2[] = {88, 65, 76, 49, 80, 53};
    const int data2_size = (int)(sizeof(data2)/sizeof(*data2));
    double angles2[] = {340, 310, 340, 210, 30, 300};
    const int angles2_size = (int)(sizeof(angles2)/sizeof(*angles2));

    // The labels on the angular axis (spokes)
    const char* labels[] = {"North", "North\nEast", "East", "South\nEast", "South", "South\nWest",
        "West", "North\nWest"};
    const int labels_size = (int)(sizeof(labels)/sizeof(*labels));

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

    // Add a title to the chart at the top left corner using 15pt Arial Bold Italic font
    c->addTitle(Chart::TopLeft, "<*underline=2*>Plants in Wonderland", "arialbi.ttf", 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, "arialbd.ttf", 9)->setAlignment(Chart::TopRight);

    // Set angular axis as 0 - 360, either 8 spokes
    c->angularAxis()->setLinearScale(0, 360, StringArray(labels, labels_size));

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

    // Add a blue (0xff) polar line layer to the chart using (data0, angle0)
    PolarLineLayer* layer0 = c->addLineLayer(DoubleArray(data0, data0_size), 0x0000ff,
        "Immortal Weed");
    layer0->setAngles(DoubleArray(angles0, angles0_size));

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

    // Add a red (0xff0000) polar line layer to the chart using (data1, angles1)
    PolarLineLayer* layer1 = c->addLineLayer(DoubleArray(data1, data1_size), 0xff0000,
        "Precious Flower");
    layer1->setAngles(DoubleArray(angles1, angles1_size));

    // 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(Chart::DiamondSymbol, 11);

    // Add a green (0x00ff00) polar line layer to the chart using (data2, angles2)
    PolarLineLayer* layer2 = c->addLineLayer(DoubleArray(data2, data2_size), 0x00ff00,
        "Magical Tree");
    layer2->setAngles(DoubleArray(angles2, angles2_size));

    // 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(Chart::SquareSymbol, 9);

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

    //free up resources
    delete c;

    return 0;
}