1st order filter

OxyPlotExample/GettingStarted/Filter/HighPassFilter.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace GettingStarted.Filter
+{
+    class HighPassFilter : IFilter
+    {
+        private double _alpha;
+        private double _previousOutput;
+        private double _previouseInput;
+
+        public HighPassFilter(double alpha)
+        {
+            if (alpha < 0.0 || alpha > 1.0)
+                throw new ArgumentException(nameof(alpha), "Alpha must be between 0 and 1.");
+
+            _alpha = alpha;
+            _previousOutput = 0.0;
+            _previouseInput = 0.0;
+        }
+
+        public double Filter(double input)
+        {
+            double output = _alpha * (_previousOutput + input - _previouseInput);
+            _previousOutput = output;
+            _previouseInput = input;
+
+            return output;
+        }
+    }
+}

OxyPlotExample/GettingStarted/Filter/IFilter.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace GettingStarted.Filter
+{
+    interface IFilter
+    {
+        public double Filter(double value);
+    }
+}

OxyPlotExample/GettingStarted/Filter/LowPassFilter.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace GettingStarted.Filter
+{
+    class LowPassFilter : IFilter
+    {
+        private double _alpha;
+        private double _previousOutput;
+
+        public LowPassFilter(double alpha)
+        {
+            if (alpha < 0.0 || alpha > 1.0)
+                throw new ArgumentException(nameof(alpha), "Alpha must be between 0 and 1.");
+
+            _alpha = alpha;
+            _previousOutput = 0.0;
+        }
+
+        public double Filter(double input)
+        {
+            double output = _previousOutput + _alpha * (input - _previousOutput);
+            _previousOutput = output;
+
+            return output;
+        }
+    }
+}

OxyPlotExample/GettingStarted/ViewModels/MainViewModel3.cs

@@ -10,6 +10,7 @@ using System.Threading.Tasks;
 using System.Timers;
 using System.Windows;
 using OxyPlot.Axes;
+using GettingStarted.Filter;
 
 namespace GettingStarted.ViewModels
 {
@@ -24,14 +25,22 @@ namespace GettingStarted.ViewModels
 
 
         [ObservableProperty]
-        private double _cutOffSecond;
+        private LineSeries _lpfSeries;
+
+
 
+        [ObservableProperty]
+        private double _cutOffSecond;
 
 
+        private IFilter _filter;
         public MainViewModel3()
         {
             MyModel = new PlotModel() { Title = "Getting Started with RT Plot", PlotMargins = new OxyThickness(50, 10, 50, 50) };
             LineSeries = new LineSeries() { Title = "Dynamic Data" };
+            LpfSeries = new LineSeries() { Title = "Filtered" };
+
+            _filter = new HighPassFilter(0.5);
 
             DateTimeAxis timeAxis = new DateTimeAxis()
             {
@@ -53,6 +62,7 @@ namespace GettingStarted.ViewModels
             MyModel.Axes.Add(linearAxis);
 
             MyModel.Series.Add(LineSeries);
+            MyModel.Series.Add(LpfSeries);
 
             CutOffSecond = 10d;
 
@@ -72,11 +82,13 @@ namespace GettingStarted.ViewModels
                 DateTime now = DateTime.Now;
 
                 double noise = (_rand.NextDouble() - 0.5) * _noiseLevel;
-                //LineSeries.Points.Add(new DataPoint(_lastX, Math.Sin(_lastX * 0.1) + noise));
-                LineSeries.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Now), Math.Sin(_lastX * 0.1) + noise));
+                double value = Math.Sin(_lastX * 0.1) + noise;
+                LineSeries.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Now), value));
+                LpfSeries.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Now), _filter.Filter(value)));
                 
                 DateTime cutOff = now.AddSeconds(-1 * CutOffSecond);
                 LineSeries.Points.RemoveAll(d => DateTimeAxis.ToDateTime(d.X) < cutOff);
+                LpfSeries.Points.RemoveAll(d => DateTimeAxis.ToDateTime(d.X) < cutOff);
 
                 if (MyModel.Axes[0] is DateTimeAxis timeAxis)
                 {