Heat Map series are represented by the NHeatMapSeries type. An instance of this type must be added to the series collection of a Cartesian chart:

NHeatMapSeries heatMap = new NHeatMapSeries();
chart.Series.Add(heatMap);

The heat map series has an associated object of type NGridData which is accessible from the Data property of the series. This object represents a two dimensional matrix of double values. Before setting values in the matrix you must first initialize the grid data dimensions by using the Size property. The following code snippet shows how to create a simple 2x2 matrix:

NGridData data = heatMap.Data;
data.Size = new NSizeI(2, 2);
data.SetValue(0, 0, 0.0);
data.SetValue(0, 1, 1.0);
data.SetValue(1, 0, 2.0);
data.SetValue(1, 1, 3.0);

If you want to pass large amounts of data to the grid you can also use the SetRange method:

data.Size = new NSizeI(2, 2);
double[,] values = new double[,] { { 0.0, 1.0 }, { 2.0, 3.0 } };
data.SetRange(0, 0, values);

The mapped dimensions of the grid data object on the horizontal and vertical axes of the series are controlled from the OriginX, OriginY, StepX, and StepY properties of the NGridData object:

data.OriginX = 10;
data.OriginY = 10;
data.StepX = 10;
data.StepY = 20;

The heat map chart has an associated palette that is accessible from the Palette property. The code below assigns a two-color palette that colors the values in the heat map matrix from Red to Green:

heatMap.Palette = new NTwoColorPalette(NColor.Red, NColor.Green);

The heat map series can also show contour lines that display areas in the heat map matrix with equal value. To show contour lines for different palette value levels you need to first assign a proper palette - usually, this is an instance of the NColorValuePalette which associates a color with a specified value:

heatMap.Palette = new NColorValuePalette(new NColorValuePair[] { new NColorValuePair(0.0, NColor.Purple),
new NColorValuePair(1.5, NColor.MediumSlateBlue),
new NColorValuePair(3.0, NColor.CornflowerBlue),
new NColorValuePair(4.5, NColor.LimeGreen),
new NColorValuePair(6.0, NColor.LightGreen),
new NColorValuePair(7.5, NColor.Yellow),
new NColorValuePair(9.0, NColor.Orange),
new NColorValuePair(10.5, NColor.Red) });

Then you need to enable contour lines using the ContourDisplayMode property:

heatMap.ContourDisplayMode = ENContourDisplayMode.Contour;

The following table shows the available options:

 When contour lines are visible you can also control their stroke and color. This is achieved from the ContourStroke and ContourColorMode properties. The latter accepts values from the ENContourColorMode enum:

Charts