IMSL C# Programmers Guide
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Charting 2D Types >> Heatmap |
Heatmap
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.
Example
In this example a two-dimensional array of data is plotted as a heatmap. The red-
blue colormap is used. The heatmap legend is enabled by settings its IsVisible
property to true.
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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