GC-88: General Discrete Distribution estimation function couldn't han…

…dle observations with negative values.
dsblank · Feb 8, 2014 · 5b65829 · 5b65829
1 parent b4f144b
commit 5b65829
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Showing 2 changed files with 46 additions and 5 deletions.
diff --git a/Sources/Accord.Statistics/Distributions/Univariate/Discrete/GeneralDiscreteDistribution.cs b/Sources/Accord.Statistics/Distributions/Univariate/Discrete/GeneralDiscreteDistribution.cs
@@ -23,11 +23,11 @@
 namespace Accord.Statistics.Distributions.Univariate
 {
     using System;
+    using System.Globalization;
     using Accord.Math;
-    using Accord.Statistics.Distributions.Fitting;
     using Accord.Statistics.Distributions;
+    using Accord.Statistics.Distributions.Fitting;
     using AForge;
-    using System.Globalization;
 
     /// <summary>
     ///   Univariate general discrete distribution, also referred as the
@@ -494,15 +494,16 @@ public void Fit(double[] observations, double[] weights, GeneralDiscreteOptions
             if (weights == null)
             {
                 for (int i = 0; i < observations.Length; i++)
-                    p[(int)observations[i]]++;
+                    p[(int)observations[i] - start]++;
             }
             else
             {
                 if (observations.Length != weights.Length)
-                    throw new ArgumentException("The weight vector should have the same size as the observations", "weights");
+                    throw new ArgumentException("The weight vector should have the same size as the observations",
+                        "weights");
 
                 for (int i = 0; i < observations.Length; i++)
-                    p[(int)observations[i]] += weights[i] * observations.Length;
+                    p[(int)observations[i] - start] += weights[i] * observations.Length;
             }
 
             if (useLaplace)

diff --git a/...ord.Tests.Statistics/Distributions/Univariate/Discrete/GeneralDiscreteDistributionTest.cs b/...ord.Tests.Statistics/Distributions/Univariate/Discrete/GeneralDiscreteDistributionTest.cs
@@ -155,6 +155,46 @@ public void FitTest2()
             Assert.IsTrue(Matrix.IsEqual(expected, actual2));
         }
 
+        [TestMethod()]
+        public void FitTest3()
+        {
+            GeneralDiscreteDistribution target = new GeneralDiscreteDistribution(-1, 4);
+            double[] values = { 0.00, 1.00, 2.00, 3.00 };
+            double[] weights = { 0.25, 0.25, 0.25, 0.25 };
+
+            target.Fit(values.Subtract(1), weights);
+
+            double[] expected = { 0.25, 0.25, 0.25, 0.25 };
+            double[] actual = target.Frequencies;
+
+            Assert.IsTrue(Matrix.IsEqual(expected, actual));
+        }
+
+        [TestMethod()]
+        public void FitTest4()
+        {
+            double[] expected = { 0.50, 0.00, 0.25, 0.25 };
+
+            GeneralDiscreteDistribution target;
+
+            double[] values = { 0.00, 2.00, 3.00 };
+            double[] weights = { 0.50, 0.25, 0.25 };
+            target = new GeneralDiscreteDistribution(-1, 4);
+            target.Fit(values.Subtract(1), weights);
+            double[] actual = target.Frequencies;
+
+            Assert.IsTrue(Matrix.IsEqual(expected, actual));
+
+            // --
+
+            double[] values2 = { 0.00, 0.00, 2.00, 3.00 };
+            double[] weights2 = { 0.25, 0.25, 0.25, 0.25 };
+            target = new GeneralDiscreteDistribution(-1, 4);
+            target.Fit(values2.Subtract(1), weights2);
+            double[] actual2 = target.Frequencies;
+            Assert.IsTrue(Matrix.IsEqual(expected, actual2));
+        }
+
 
         [TestMethod()]
         public void DistributionFunctionTest()