ChartDirector 6.0 (C++ Edition)

Polar Vector Chart




This example demonstrates a polar vector chart.

A vector chart is like a scatter chart, but the symbols are arrows which can be of arbitrary lengths pointing to arbitrary directions. Thus each symbol in a vector chart is specified by 4 values - the radial and angular coordinates, and the length and the direction.

In ChartDirector, a polar vector layer is created using PolarChart.addVectorLayer.

Source Code Listing

[The following code is available in "cppdemo/polarvector". 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[])
{
    // Coordinates of the starting points of the vectors
    double radius[] = {5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
        10, 10, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 20, 20, 20, 20, 20, 20, 20, 20, 20,
        20, 20, 20, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25};
    double angle[] = {0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120,
        150, 180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0,
        30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120, 150, 180, 210, 240,
        270, 300, 330};

    // Magnitude and direction of the vectors
    double magnitude[] = {5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3,
        3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1};
    double direction[] = {60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120, 150,
        180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0, 30,
        60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 0, 30, 60, 90, 120, 150, 180, 210, 240, 270,
        300, 330, 0, 30};

    // 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("Polar Vector Chart Demonstration", "arialbi.ttf", 15);

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

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

    // Set angular axis as 0 - 360, with a spoke every 30 units
    c->angularAxis()->setLinearScale(0, 360, 30);

    // Add a polar vector layer to the chart with blue (0000ff) vectors
    c->addVectorLayer(DoubleArray(radius, (int)(sizeof(radius) / sizeof(radius[0]))), DoubleArray(
        angle, (int)(sizeof(angle) / sizeof(angle[0]))), DoubleArray(magnitude, (int)(sizeof(
        magnitude) / sizeof(magnitude[0]))), DoubleArray(direction, (int)(sizeof(direction) /
        sizeof(direction[0]))), Chart::RadialAxisScale, 0x0000ff);

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

    //free up resources
    delete c;
    return 0;
}