ScottPlot.NET
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Multi-Axis

Additional axes may be added to plots. Plottables are displayed using the coordinate system of the primary axes by default, but any plottable can be displayed using any X and Y axis.

This code sample is specific to ScottPlot 5 (details)
ScottPlot.Plot myPlot = new();

// plottables use the standard X and Y axes by default
var sig1 = myPlot.Add.Signal(ScottPlot.Generate.Sin(51, mult: 0.01));
sig1.Axes.XAxis = myPlot.Axes.Bottom; // standard X axis
sig1.Axes.YAxis = myPlot.Axes.Left; // standard Y axis
myPlot.Axes.Left.Label.Text = "Primary Y Axis";

// create a second axis and add it to the plot
var yAxis2 = myPlot.Axes.AddLeftAxis();

// add a new plottable and tell it to use the custom Y axis
var sig2 = myPlot.Add.Signal(ScottPlot.Generate.Cos(51, mult: 100));
sig2.Axes.XAxis = myPlot.Axes.Bottom; // standard X axis
sig2.Axes.YAxis = yAxis2; // custom Y axis
yAxis2.Label.Text = "Secondary Y Axis";

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

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