A Heatmap divides a rectangle into subrectangles. The color of each subrectangle is determined by the value of a data array and a colormap.

If the data array is m by n then there are m divisions along the x-axis and n divisions along the y-axis.

A Colormap is a mapping from [0,1] to color values. The blue-red colormap, used in the example below, maps 0 to red and 1 to dark blue and interpolates between these endpoints values. The heatmap maps the minimum data value to the color corresponding to 0 and the highest data value to the color corresponding to 1.

The Heatmap class has a special legend for colormaps. It displays the color values as a gradient labeled with corresponding data values.


In this example a two-dimensional array of data is plotted as a heatmap. The “red-blue” Colormap is used. The HeatmapLegend is enabled by setting its IsVisible property to true.


(Download Code)


using Imsl.Chart2D;


public class SampleHeatmap : FrameChart {


    public SampleHeatmap() {

        Chart chart = this.Chart;

        AxisXY axis = new AxisXY(chart);


        double xmin = 0.0;

        double xmax = 5.0;

        double ymin = 0.0;

        double ymax = 4.0;

        double zmin = 0.0;

        double zmax = 100.0;

        double[,] data = new double [,] {

            {23, 48, 16, 56},

            {89, 74, 54, 32},

            {12, 45, 18,  9},

            {72, 15, 42, 92},

            {63, 36, 78, 29}


        Heatmap heatmap = new Heatmap(axis, xmin, xmax, ymin, ymax,

            zmin, zmax, data, Colormap_Fields.BLUE_RED);

        heatmap.HeatmapLegend.IsVisible = true;



    public static void Main(string[] argv) {

        System.Windows.Forms.Application.Run(new SampleHeatmap());




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