Contour Plot

Rectangular Contour Plot

A rectangular contour plot with evenly spaced points can be created from a 2D array of 3D points.

ScottPlot.Plot myPlot = new();

Coordinates3d[,] cs = new Coordinates3d[50, 50];
for (int y = 0; y < cs.GetLength(0); y++)
{
    for (int x = 0; x < cs.GetLength(1); x++)
    {
        double z = Math.Sin(x * .1) + Math.Cos(y * .1);
        cs[y, x] = new(x, y, z);
    }
}

var contour = myPlot.Add.ContourLines(cs);
contour.LineColor = Colors.Black.WithAlpha(.5);
contour.LinePattern = LinePattern.Dotted;

myPlot.Axes.TightMargins();
myPlot.HideGrid();

myPlot.SavePng("demo.png", 400, 300);

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Irregular Contour Plot

A contour plot can be created from a collection of 3D data points placed arbitrarily in X/Y plane.

Contour.cs

ScottPlot.Plot myPlot = new();

// generate irregularly spaced X/Y/Z data points
Coordinates3d[] cs = new Coordinates3d[1000];
for (int i = 0; i < cs.Length; i++)
{
    double x = Generate.RandomNumber(0, Math.PI * 2);
    double y = Generate.RandomNumber(0, Math.PI * 2);
    double z = Math.Sin(x) + Math.Cos(y);
    cs[i] = new(x, y, z);
}

// place markers at each data point
double minZ = cs.Select(x => x.Z).Min();
double maxZ = cs.Select(x => x.Z).Max();
double spanZ = maxZ - minZ;
IColormap cmap = new ScottPlot.Colormaps.MellowRainbow();
for (int i = 0; i < cs.Length; i++)
{
    double fraction = (cs[i].Z - minZ) / (spanZ);
    var marker = myPlot.Add.Marker(cs[i].X, cs[i].Y);
    marker.Color = cmap.GetColor(fraction).WithAlpha(.8);
    marker.Size = 5;
}

// show contour lines
var contour = myPlot.Add.ContourLines(cs);

// style the plot
myPlot.Axes.TightMargins();
myPlot.HideGrid();

myPlot.SavePng("demo.png", 400, 300);

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Contour Lines with Heatmap

Contour lines may be placed on top of heatmaps.

Contour.cs

ScottPlot.Plot myPlot = new();

Coordinates3d[,] cs = new Coordinates3d[50, 50];
for (int y = 0; y < cs.GetLength(0); y++)
{
    for (int x = 0; x < cs.GetLength(1); x++)
    {
        double z = Math.Sin(x * .1) + Math.Cos(y * .1);
        cs[y, x] = new(x, y, z);
    }
}

var heatmap = myPlot.Add.Heatmap(cs);
heatmap.FlipVertically = true;
heatmap.Colormap = new ScottPlot.Colormaps.MellowRainbow();

var contour = myPlot.Add.ContourLines(cs);
contour.LabelStyle.Bold = true;
contour.LinePattern = LinePattern.DenselyDashed;
contour.LineColor = Colors.Black.WithAlpha(.5);

myPlot.Axes.TightMargins();
myPlot.HideGrid();

myPlot.SavePng("demo.png", 400, 300);

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Contour Lines with Colormap

If a colormap is provided it will be used to color each line in the colormap according to its value.

Contour.cs

ScottPlot.Plot myPlot = new();

Coordinates3d[,] cs = new Coordinates3d[50, 50];
for (int y = 0; y < cs.GetLength(0); y++)
{
    for (int x = 0; x < cs.GetLength(1); x++)
    {
        double z = Math.Sin(x * .1) + Math.Cos(y * .1);
        cs[y, x] = new(x, y, z);
    }
}

var cl = myPlot.Add.ContourLines(cs, count: 25);
cl.Colormap = new ScottPlot.Colormaps.MellowRainbow();
cl.LineWidth = 3;
cl.LabelStyle.IsVisible = false;

myPlot.Axes.TightMargins();
myPlot.HideGrid();

myPlot.SavePng("demo.png", 400, 300);

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