Fix DataFrame Null Math (#6661)

* Fix math and update templates to match generated files.

* Add Tests

* Fix test

* Same issue?

* Test and Fix Median and Mean

* Update Cumulative handling of nulls based on DataFrame documentation

Author: JakeRadMSFT

src/Microsoft.Data.Analysis/DataFrame.BinaryOperators.tt

@@ -18,7 +18,7 @@ namespace Microsoft.Data.Analysis
 {
     public partial class DataFrame
     {
-        #pragma warning disable 1591
+#pragma warning disable 1591
 <# foreach (MethodConfiguration method in methodConfiguration) { #>
 <# if (method.MethodType == MethodType.BinaryScalar) { #>
 <# if (method.IsBitwise == true) { #>
@@ -32,7 +32,7 @@ namespace Microsoft.Data.Analysis
         {
             return df.<#=method.MethodName#>(value);
         }
-        
+
         public static DataFrame operator <#=method.Operator#>(<#=type.TypeName#> value, DataFrame df)
         {
             return df.Reverse<#=method.MethodName#>(value);

src/Microsoft.Data.Analysis/DataFrameColumn.BinaryOperators.tt

@@ -18,7 +18,7 @@ namespace Microsoft.Data.Analysis
 {
     public abstract partial class DataFrameColumn
     {
-        #pragma warning disable 1591
+#pragma warning disable 1591
 <# foreach (MethodConfiguration method in methodConfiguration) { #>
 <# if (method.MethodType == MethodType.BinaryScalar) { #>
 <# if (method.IsBitwise == true) { #>

src/Microsoft.Data.Analysis/PrimitiveColumnContainer.BinaryOperations.tt

@@ -18,15 +18,15 @@ namespace Microsoft.Data.Analysis
     {
 <# foreach (MethodConfiguration method in methodConfiguration) { #>
 <# if (method.MethodType == MethodType.Comparison || method.MethodType == MethodType.ComparisonScalar) { #>
-       public <#= method.GetSingleArgumentMethodSignature("PrimitiveColumnContainer", "T") #>
-       {
+        public <#= method.GetSingleArgumentMethodSignature("PrimitiveColumnContainer", "T") #>
+        {
 <# if (method.MethodType == MethodType.ComparisonScalar ) { #>
             PrimitiveDataFrameColumnArithmetic<T>.Instance.<#=method.MethodName#>(this, scalar, ret);
 <# } else { #>
             PrimitiveDataFrameColumnArithmetic<T>.Instance.<#=method.MethodName#>(this, right, ret);
 <# } #>
             return this;
-       }
+        }
 
 <# } else { #>
         public <#= method.GetSingleArgumentMethodSignature("PrimitiveColumnContainer", "T")#>
@@ -45,11 +45,11 @@ namespace Microsoft.Data.Analysis
 <# } #>
 <# foreach (MethodConfiguration method in methodConfiguration) { #>
 <# if (method.MethodType == MethodType.BinaryScalar) { #>
-       public PrimitiveColumnContainer<T> Reverse<#=method.MethodName#>(T scalar)
-       {
+        public PrimitiveColumnContainer<T> Reverse<#=method.MethodName#>(T scalar)
+        {
             PrimitiveDataFrameColumnArithmetic<T>.Instance.<#=method.MethodName#>(scalar, this);
             return this;
-       }
+        }
 <# } #>
 <# } #>
     }

src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs

@@ -228,7 +228,7 @@ public override double Median()
             PrimitiveDataFrameColumn<long> sortIndices = GetAscendingSortIndices(out Int64DataFrameColumn _);
             long middle = sortIndices.Length / 2;
             double middleValue = (double)Convert.ChangeType(this[sortIndices[middle].Value].Value, typeof(double));
-            if (Length % 2 == 0)
+            if (sortIndices.Length % 2 == 0)
             {
                 double otherMiddleValue = (double)Convert.ChangeType(this[sortIndices[middle - 1].Value].Value, typeof(double));
                 return (middleValue + otherMiddleValue) / 2;
@@ -243,7 +243,7 @@ public override double Mean()
         {
             if (Length == 0)
                 return 0;
-            return (double)Convert.ChangeType((T)Sum(), typeof(double)) / Length;
+            return (double)Convert.ChangeType((T)Sum(), typeof(double)) / (Length - NullCount);
         }
 
         protected internal override void Resize(long length)