Example: Heatmap from Color array

A 5 by 10 data array is created by linearly interpolating from the lower left corner to the upper right corner and adding in a uniform random variable. A red temperature color map is used. This maps the minimum data value to light green and the maximum data value to dark green.

The legend is enabled by setting its paint attribute to true.

import com.imsl.chart.*;
import java.awt.Color;
import java.util.Random;

public class HeatmapEx2 extends javax.swing.JApplet  {

    public void init() {
        Chart chart = new Chart(this);
        JPanelChart panel = new JPanelChart(chart);
        getContentPane().add(panel, java.awt.BorderLayout.CENTER);
        setup(chart);
    }

    static private void setup(Chart chart) {
        JFrameChart jfc = new JFrameChart();
        AxisXY axis = new AxisXY(chart);

        int nx = 5;
        int ny = 10;
        double xmin = 0.0;
        double xmax = 10.0;
        double ymin = -3.0;
        double ymax = 2.0;
        double fmin = 0.0;
        double fmax = nx + ny - 1;

        double data[][] = new double[nx][ny];
        Random random = new Random(123457L);
        for (int i = 0;  i < nx;  i++) {
            for (int j = 0;  j < ny;  j++) {
                data[i][j] = i + j + random.nextDouble();
            }
        }
        Heatmap heatmap = new Heatmap(axis, xmin, xmax, ymin, ymax, 0.0, fmax,
            data, Colormap.RED_TEMPERATURE);
        heatmap.getHeatmapLegend().setPaint(true);
        heatmap.getHeatmapLegend().setTitle("Heat");
    }

    public static void main(String argv[]) throws Exception {
        JFrameChart frame = new JFrameChart();
        HeatmapEx2.setup(frame.getChart());
        frame.show();
    }
}

Output

Link to Java source.