added mean to azimuth

Source/Meadow.Units.Tests/AzimuthTests.cs

@@ -1,76 +1,134 @@
 using System;
+using System.Collections.Generic;
 using Xunit;
 
-namespace Meadow.Units.Tests
+namespace Meadow.Units.Tests;
+
+
+public class AzimuthTests
 {
+    private Random _random = new Random();
 
-    public class AzimuthTests
+    [Fact]
+    public void ConstructorTests()
     {
-        private Random _random = new Random();
-
-        [Fact]
-        public void ConstructorTests()
+        foreach (Angle.UnitType unit in Enum.GetValues(typeof(Angle.UnitType)))
         {
-            foreach (Angle.UnitType unit in Enum.GetValues(typeof(Angle.UnitType)))
-            {
-                var value = _random.NextDouble() * 360;
-                var a = new Angle(value, unit);
-                var p = typeof(Angle).GetProperty(Enum.GetName(typeof(Angle.UnitType), unit));
+            var value = _random.NextDouble() * 360;
+            var a = new Angle(value, unit);
+            var p = typeof(Angle).GetProperty(Enum.GetName(typeof(Angle.UnitType), unit));
 
-                Assert.Equal(Math.Round(value, 6), Math.Round((double)p.GetValue(a), 6));
-            }
+            Assert.Equal(Math.Round(value, 6), Math.Round((double)p.GetValue(a), 6));
+        }
 
-            Azimuth az = new Azimuth(0d);
-            Assert.True(az.DecimalDegrees == 0);
+        Azimuth az = new Azimuth(0d);
+        Assert.True(az.DecimalDegrees == 0);
 
-            Azimuth a2 = new Azimuth();
-            Assert.True(a2.DecimalDegrees == 0);
+        Azimuth a2 = new Azimuth();
+        Assert.True(a2.DecimalDegrees == 0);
 
-            Azimuth a3 = Azimuth.FromCompass16PointCardinalName(Azimuth16PointCardinalNames.E);
-            Assert.True(a3.Compass16PointCardinalName == Azimuth16PointCardinalNames.E);
-            Assert.Equal(90d, a3.DecimalDegrees);
+        Azimuth a3 = Azimuth.FromCompass16PointCardinalName(Azimuth16PointCardinalNames.E);
+        Assert.True(a3.Compass16PointCardinalName == Azimuth16PointCardinalNames.E);
+        Assert.Equal(90d, a3.DecimalDegrees);
 
-            Azimuth v4 = Azimuth.FromDecimalDegrees(270);
-            Assert.True(v4.DecimalDegrees == 270);
-        }
+        Azimuth v4 = Azimuth.FromDecimalDegrees(270);
+        Assert.True(v4.DecimalDegrees == 270);
+    }
 
-        [Fact()]
-        public void ConversionTests()
-        {
-            Azimuth v = new Azimuth(90);
-            Assert.True(v.Compass16PointCardinalName == Azimuth16PointCardinalNames.E);
+    [Fact()]
+    public void ConversionTests()
+    {
+        Azimuth v = new Azimuth(90);
+        Assert.True(v.Compass16PointCardinalName == Azimuth16PointCardinalNames.E);
 
-            Azimuth v2 = new Azimuth(Azimuth16PointCardinalNames.NNW);
-            Assert.True(v2.DecimalDegrees == 337.5);
+        Azimuth v2 = new Azimuth(Azimuth16PointCardinalNames.NNW);
+        Assert.True(v2.DecimalDegrees == 337.5);
 
-            Azimuth v3 = new Azimuth(191.25);
-            Assert.True(v3.Compass16PointCardinalName == Azimuth16PointCardinalNames.SSW);
+        Azimuth v3 = new Azimuth(191.25);
+        Assert.True(v3.Compass16PointCardinalName == Azimuth16PointCardinalNames.SSW);
 
-        }
+    }
 
-        [Fact()]
-        public void MathTests()
-        {
-            // first do some simple known-value tests
-            var a1 = new Azimuth(270);
-            var a2 = a1 + new Azimuth(180);
-            Assert.Equal(90d, a2.DecimalDegrees);
+    [Fact()]
+    public void MathTests()
+    {
+        // first do some simple known-value tests
+        var a1 = new Azimuth(270);
+        var a2 = a1 + new Azimuth(180);
+        Assert.Equal(90d, a2.DecimalDegrees);
+
+        var a3 = new Azimuth(90);
+        var a4 = a3 - new Azimuth(180);
+        Assert.Equal(270d, a4.DecimalDegrees);
+
+        var a5 = a3 * 5;
+        Assert.Equal(90d, a5.DecimalDegrees);
 
-            var a3 = new Azimuth(90);
-            var a4 = a3 - new Azimuth(180);
-            Assert.Equal(270d, a4.DecimalDegrees);
+        var m = new Azimuth(90) * 5;
+        Assert.Equal(90d, m.DecimalDegrees);
 
-            var a5 = a3 * 5;
-            Assert.Equal(90d, a5.DecimalDegrees);
+        var m2 = new Azimuth(90) * -1;
+        Assert.Equal(270d, m2.DecimalDegrees);
 
-            var m = new Azimuth(90) * 5;
-            Assert.Equal(90d, m.DecimalDegrees);
+        var m3 = new Azimuth(360 * 5.5);
+        Assert.Equal(180d, m3.DecimalDegrees);
+    }
 
-            var m2 = new Azimuth(90) * -1;
-            Assert.Equal(270d, m2.DecimalDegrees);
+    [Fact]
+    public void ExtensionTests()
+    {
+        var count = 5;
+        var range = 20;
+        var middle = 45;
+        var samples = new List<Azimuth>();
 
-            var m3 = new Azimuth(360 * 5.5);
-            Assert.Equal(180d, m3.DecimalDegrees);
+        // test mean around 45
+        for (var i = 0; i < count; i++)
+        {
+            samples.Add(new Azimuth(_random.Next(middle - (range / 2), middle + (range / 2))));
+        }
+        var mean = samples.Mean();
+        Assert.True(mean.DecimalDegrees > (middle - (range / 2)));
+        Assert.True(mean.DecimalDegrees < (middle + (range / 2)));
+
+        // test mean around 270
+        middle = 270;
+        samples.Clear();
+        for (var i = 0; i < count; i++)
+        {
+            samples.Add(new Azimuth(_random.Next(middle - (range / 2), middle + (range / 2))));
+        }
+        mean = samples.Mean();
+        Assert.True(mean.DecimalDegrees > (middle - (range / 2)));
+        Assert.True(mean.DecimalDegrees < (middle + (range / 2)));
+
+        // test mean around 180
+        middle = 180;
+        samples.Clear();
+        for (var i = 0; i < count; i++)
+        {
+            samples.Add(new Azimuth(_random.Next(middle - (range / 2), middle + (range / 2))));
         }
+        mean = samples.Mean();
+        Assert.True(mean.DecimalDegrees > (middle - (range / 2)));
+        Assert.True(mean.DecimalDegrees < (middle + (range / 2)));
+
+        // test mean around 0
+        middle = 0;
+        samples.Clear();
+        for (var i = 0; i < count; i++)
+        {
+            samples.Add(new Azimuth(_random.Next(middle - (range / 2), middle + (range / 2))));
+        }
+        mean = samples.Mean();
+        if (mean.DecimalDegrees > 270)
+        {
+            Assert.True(mean.DecimalDegrees > (360 - (range / 2)));
+        }
+        else
+        {
+            Assert.True(mean.DecimalDegrees < (0 + (range / 2)));
+        }
+
     }
 }

Source/Meadow.Units/Extensions/AzimuthExtensions.cs

@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Meadow.Units;
+
+/// <summary>
+/// Provides extension methods for creating <see cref="Azimuth"/> instances.
+/// </summary>
+public static class AzimuthExtensions
+{
+    /// <summary>
+    /// calculates a mean Azimuth
+    /// </summary>
+    /// <param name="samples"></param>
+    /// <returns></returns>
+    public static Azimuth Mean(this IEnumerable<Azimuth> samples)
+    {
+        // if we have samples that straddle zero (i.e. some > 270 and some < 90), we need to adjust
+        if (samples.Any(s => s.DecimalDegrees > 270) && samples.Any(s => s.DecimalDegrees < 90))
+        {
+            // adjust all > 270 samples to negatives
+            var adjusted = samples.Select(s => s.DecimalDegrees > 270 ? s.DecimalDegrees - 360 : s.DecimalDegrees);
+            var mean = adjusted.Average();
+            if (mean < 0) mean += 360;
+            return new Azimuth(mean);
+        }
+        else
+        {
+            return new Azimuth(samples.Select(a => a.DecimalDegrees).Average());
+        }
+    }
+}

Source/Meadow.Units/Meadow.Units.sln

@@ -4,6 +4,8 @@ VisualStudioVersion = 17.7.34031.279
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Meadow.Units", "Meadow.Units.csproj", "{91B5B8E2-5E97-41C3-A38F-BC2732795D11}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Meadow.Units.Tests", "..\Meadow.Units.Tests\Meadow.Units.Tests.csproj", "{3EB4B1DA-6353-41E5-82C5-A448E532E677}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -16,6 +18,10 @@ Global
 		{91B5B8E2-5E97-41C3-A38F-BC2732795D11}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{91B5B8E2-5E97-41C3-A38F-BC2732795D11}.Release|Any CPU.Build.0 = Release|Any CPU
 		{91B5B8E2-5E97-41C3-A38F-BC2732795D11}.Release|Any CPU.Deploy.0 = Release|Any CPU
+		{3EB4B1DA-6353-41E5-82C5-A448E532E677}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{3EB4B1DA-6353-41E5-82C5-A448E532E677}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{3EB4B1DA-6353-41E5-82C5-A448E532E677}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{3EB4B1DA-6353-41E5-82C5-A448E532E677}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE