Interpolation Module #459
Description
ScottPlot could benefit from an interpolation module.
Interpolation can take a small number of X/Y values and create smooth curves from them. There are different interpolation algorithms, with linear, cosine, and cubic being some of the most common.
This website has some nice simple descriptions: http://paulbourke.net/miscellaneous/interpolation/
If implemented, interpolations may help in dynamic colormap generation. #458
There are more advanced forms of interpolation (https://en.wikipedia.org/wiki/Interpolation) so a well-designed interpolation module would be easy to extend.
Code Example
Here's some code that demonstrates the idea using cosine interpolation.
formsPlot1.plt.Clear();
int[] rXs = { 0, 50, 100, 150, 200, 255 };
int[] rYs = { 123, 222, 18, 76, 241, 164 };
double[] rInterpolated = new double[255];
for (int splineIndex = 0; splineIndex < rXs.Length - 1; splineIndex++)
{
int x1 = rXs[splineIndex];
int x2 = rXs[splineIndex + 1];
int y1 = rYs[splineIndex];
int y2 = rYs[splineIndex + 1];
int distance = x2 - x1;
for (int i = 0; i < distance; i++)
{
double muLinear = (double)i / distance;
double muCos = (1 - Math.Cos(muLinear * Math.PI)) / 2;
double mu = muCos;
rInterpolated[x1 + i] = (y1 * (1 - mu) + y2 * mu);
}
}
formsPlot1.plt.PlotScatter(
ScottPlot.Tools.DoubleArray(rXs),
ScottPlot.Tools.DoubleArray(rYs),
Color.Red, 0);
formsPlot1.plt.PlotSignal(rInterpolated);
formsPlot1.plt.Axis(0, 255, 0, 255);
formsPlot1.Render();