Merge remote-tracking branch 'upstream/develop' into transposablexyseries

objorke · objorke · commit e6b241c74e72 · 2019-10-10T23:47:47.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 - WindowsForms and Wpf support .NET Core 3.0 (#1331)
 - Added .NET Core port of PngExporter
 - New PolarPlot filling the full plot area (#1056)
+- Support for three colors in histogram series (#1305)
 - Command to copy plot to the clipboard in Windows Forms (Ctrl-C) (#1297)
 - Added Avalonia based renderer and control library (based off OxyPlot.Wpf).
 - New `InterpolationAlgorithm` property in LineSeries and PolylineAnnotation (#494)
diff --git a/Source/Examples/ExampleLibrary/Series/HistogramSeriesExamples.cs b/Source/Examples/ExampleLibrary/Series/HistogramSeriesExamples.cs
@@ -90,6 +90,12 @@ public static PlotModel DisconnectedBins()
             return CreateDisconnectedBins();
         }
 
+        [Example("Normal Distribution Three Colors")]
+        public static PlotModel NormalDistribution()
+        {
+            return CreateNormalDistribution();
+        }
+
         public static PlotModel CreateExponentialDistribution(double mean = 1, int n = 10000)
         {
             var model = new PlotModel { Title = "Exponential Distribution", Subtitle = "Uniformly distributed bins (" + n + " samples)" };
@@ -128,6 +134,43 @@ public static PlotModel CreateExponentialDistributionCustomBins(double mean = 1,
             return model;
         }
 
+        public static PlotModel CreateNormalDistribution(double mean = 0, double std = 1, int n = 1000000)
+        {
+            var model = new PlotModel { Title = $"Normal Distribution (μ={mean}, σ={std})", Subtitle = "95% of the distribution (" + n + " samples)" };
+            model.Axes.Add(new LinearAxis { Position = AxisPosition.Left, Title = "Frequency" });
+            model.Axes.Add(new LinearAxis { Position = AxisPosition.Bottom, Title = "x" });
+
+            Random rnd = new Random();
+
+            HistogramSeries chs = new HistogramSeries();
+            var binningOptions = new BinningOptions(BinningOutlierMode.CountOutliers, BinningIntervalType.InclusiveLowerBound, BinningExtremeValueMode.ExcludeExtremeValues);
+            var binBreaks = HistogramHelpers.CreateUniformBins(-std * 4, std * 4, 100);
+            chs.Items.AddRange(HistogramHelpers.Collect(SampleNormal(rnd, mean, std, n), binBreaks, binningOptions));
+            chs.StrokeThickness = 1;
+
+            double LimitHi = mean + 1.96 * std;
+            double LimitLo = mean - 1.96 * std;
+            OxyColor ColorHi = OxyColors.DarkRed;
+            OxyColor ColorLo = OxyColors.DarkRed;
+
+            chs.ColorMapping = (item) =>
+            {
+                if (item.RangeCenter > LimitHi)
+                {
+                    return ColorHi;
+                }
+                else if (item.RangeCenter < LimitLo)
+                {
+                    return ColorLo;
+                }
+                return chs.ActualFillColor;
+            };
+
+            model.Series.Add(chs);
+
+            return model;
+        }
+
         public static PlotModel CreateDisconnectedBins()
         {
             var model = new PlotModel { Title = "Disconnected Bins" };
@@ -155,5 +198,21 @@ private static double SampleExp(Random rnd, double mean)
         {
             return Math.Log(1.0 - rnd.NextDouble()) / -mean;
         }
+
+        private static IEnumerable<double> SampleNormal(Random rnd, double mean, double std, int count)
+        {
+            for (int i = 0; i < count; i++)
+            {
+                yield return SampleNormal(rnd, mean, std);
+            }
+        }
+
+        private static double SampleNormal(Random rnd, double mean, double std)
+        {
+            // http://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
+            var u1 = rnd.NextDouble();
+            var u2 = rnd.NextDouble();
+            return Math.Sqrt(-2 * Math.Log(u1)) * Math.Cos(2 * Math.PI * u2);
+        }
     }
 }
diff --git a/Source/OxyPlot/Series/HistogramItem.cs b/Source/OxyPlot/Series/HistogramItem.cs
@@ -48,6 +48,10 @@ public HistogramItem(double rangeStart, double rangeEnd, double area, int count)
         public double Area { get; set; }
 
         /// <summary>
+        /// Gets the center of the item.
+        /// </summary>
+        public double RangeCenter => this.RangeStart + ((this.RangeEnd - this.RangeStart) / 2);
+
         /// Gets or sets the count.
         /// </summary>
         /// <value>The count.</value>
diff --git a/Source/OxyPlot/Series/HistogramSeries.cs b/Source/OxyPlot/Series/HistogramSeries.cs
@@ -38,19 +38,24 @@ public class HistogramSeries : XYAxisSeries
         /// </summary>
         private bool ownsActualItems;
 
+        /// <summary>
+        /// The default color mapping.
+        /// </summary>
+        private OxyColor defaultColorMapping(HistogramItem item) => ActualFillColor;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="HistogramSeries" /> class.
         /// </summary>
         public HistogramSeries()
         {
             this.FillColor = OxyColors.Automatic;
-            this.NegativeFillColor = OxyColors.Undefined;
             this.StrokeColor = OxyColors.Black;
             this.StrokeThickness = 0;
             this.TrackerFormatString = DefaultTrackerFormatString;
             this.LabelFormatString = null;
             this.LabelFontSize = 0;
             this.LabelPlacement = LabelPlacement.Outside;
+            this.ColorMapping = defaultColorMapping;
         }
 
         /// <summary>
@@ -124,6 +129,11 @@ public OxyColor ActualFillColor
         /// </summary>
         public bool CanTrackerInterpolatePoints { get; set; }
 
+        /// <summary>
+        /// Gets or sets the delegate used to map from histogram item to color.
+        /// </summary>
+        public Func<HistogramItem, OxyColor> ColorMapping { get; set; }
+
         /// <summary>
         /// Gets or sets the delegate used to map from <see cref="ItemsSeries.ItemsSource" /> to <see cref="HistogramSeries" />. The default is <c>null</c>.
         /// </summary>
@@ -344,12 +354,7 @@ protected void RenderBins(IRenderContext rc, OxyRect clippingRect, ICollection<H
         {
             foreach (var item in items)
             {
-                // Get the color of the item
-                var actualFillColor = this.ActualFillColor;
-                if (item.Value < 0 && !this.NegativeFillColor.IsUndefined())
-                {
-                    actualFillColor = this.NegativeFillColor;
-                }
+                var actualFillColor = ColorMapping(item);
 
                 // transform the data points to screen points
                 var p1 = this.Transform(item.RangeStart, 0);
