Add Std api as method again

NumSharp.sln

@@ -13,8 +13,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NumSharp.Python", "src\NumS
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NumSharp.Core", "src\NumSharp.Core\NumSharp.Core.csproj", "{190A2514-31CD-4738-AF20-3492DD47DE8C}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NumSharp.Examples", "test\NumSharp.Examples\NumSharp.Examples.csproj", "{D8CE7D31-B5F7-4286-9D5D-3CA7781A9522}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -41,10 +39,6 @@ Global
 		{190A2514-31CD-4738-AF20-3492DD47DE8C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{190A2514-31CD-4738-AF20-3492DD47DE8C}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{190A2514-31CD-4738-AF20-3492DD47DE8C}.Release|Any CPU.Build.0 = Release|Any CPU
-		{D8CE7D31-B5F7-4286-9D5D-3CA7781A9522}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{D8CE7D31-B5F7-4286-9D5D-3CA7781A9522}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{D8CE7D31-B5F7-4286-9D5D-3CA7781A9522}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{D8CE7D31-B5F7-4286-9D5D-3CA7781A9522}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

src/NumSharp.Core/Math/NdArray.Mean.cs

@@ -16,7 +16,12 @@ public static NDArray mean(this NDArray np, int axis = -1)
             // axis == -1: DEFAULT; to compute the mean of the flattened array.
             if (axis == -1)
             {
-                var sum = np.Storage.GetData<double>().Sum();
+                var data = np.Storage.GetData();
+
+                double sum = 0;
+
+                for (int idx =0; idx < data.Length;idx++)
+                    sum += Convert.ToDouble(data.GetValue(idx)); 
 
                 mean.Storage.SetData(new double[] { sum / np.size});
             }
@@ -32,7 +37,7 @@ public static NDArray mean(this NDArray np, int axis = -1)
                         sumVec[p] += Convert.ToDouble(np[d,p]);
                     }
                 }
-                var puffer = mean.Storage.GetData<double>().ToList();
+                var puffer = mean.Storage.CloneData<double>().ToList();
 
                 for (int d = 0; d < np.shape[1]; d++)
                 {

src/NumSharp.Core/Math/NdArray.Std.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using NumSharp.Core.Extensions;
+
+namespace NumSharp.Core
+{
+    public partial class NDArray
+    {
+        public NDArray std(int axis = -1, Type dtype = null)
+        {
+            dtype = (dtype == null) ? typeof(double) : dtype;
+
+            // in case have 1D array but user still using axis 0 ... can be used like -1
+            axis = (axis == 0 && this.ndim == 1) ? -1 : axis;
+
+            Array data = this.Storage.GetData();
+
+            NDArray stdArr = new NDArray(dtype);
+
+            if (axis == -1)
+            {
+                double mean = this.mean(axis).MakeGeneric<double>()[0];
+                double sum = 0;
+                for(int idx = 0; idx < data.Length;idx++)                
+                    sum += Math.Pow(Convert.ToDouble(data.GetValue(idx)) - mean,2);
+
+                double stdValue = Math.Sqrt(sum / this.size);
+                stdArr.Storage.Allocate(dtype,new Shape(1),1);
+                var puffer = Array.CreateInstance(dtype,1);
+                puffer.SetValue(stdValue,0);
+                stdArr.Storage.SetData(puffer);
+            }
+            else 
+            {
+                double[] stdValue = null;
+                if (axis == 0)
+                {
+                    double[] sum = new double[this.shape[1]];
+                    stdValue = new double[sum.Length];
+
+                    double[] mean = this.mean(axis).Storage.GetData<double>();
+
+                    for (int idx = 0; idx < sum.Length;idx++)
+                    {
+                        for(int jdx =0; jdx < this.shape[0];jdx++)
+                        {
+                            sum[idx] += Math.Pow(Convert.ToDouble(this[jdx,idx]) - mean[idx],2); 
+                        }
+                        stdValue[idx] = Math.Sqrt(sum[idx] / this.shape[0]);
+                    }
+
+                }
+                else if (axis == 1)
+                {
+                    double[] sum = new double[this.shape[0]];
+                    stdValue = new double[sum.Length];
+
+                    double[] mean = this.mean(axis).Storage.GetData<double>();
+
+                    for (int idx = 0; idx < sum.Length;idx++)
+                    {
+                        for(int jdx =0; jdx < this.shape[1];jdx++)
+                        {
+                            sum[idx] += Math.Pow(Convert.ToDouble(this[idx,jdx]) - mean[idx],2); 
+                        }
+                        stdValue[idx] = Math.Sqrt(sum[idx] / this.shape[1]);
+                    }
+                }
+                else
+                {
+                    throw new NotImplementedException();
+                }
+                stdArr.Storage.Allocate(dtype,new Shape(stdValue.Length),1);
+                stdArr.Storage.SetData(stdValue);
+            }
+            return stdArr;
+        }
+    }
+}

src/NumSharp.Core/NumSharp.Core.csproj

@@ -43,8 +43,6 @@ Add axis arg in ndarray.roll.</PackageReleaseNotes>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <DebugType>full</DebugType>
-    <DebugSymbols>true</DebugSymbols>
   </PropertyGroup>
 
   <ItemGroup Condition="$([System.Text.RegularExpressions.Regex]::IsMatch('$(TargetFramework)', '^net\d'))">

test/NumSharp.UnitTest/Creation/np.random.normal.Test.cs

@@ -24,8 +24,8 @@ public void NormalDistributionTest()
             Assert.IsTrue(s.shape[0] == 10);
             Assert.IsTrue(s.shape[1] == 100);
 
-            // var std = np.std(s, ddof = 1);
-            // Assert.IsTrue(Math.Abs(sigma - std)) < 0.01;
+            var std = s.std();
+            Assert.IsTrue(Math.Abs(sigma - std.Storage.GetData<double>()[0] )  < 0.01);
         }
     }
 }

test/NumSharp.UnitTest/Extensions/NDArray.Std.Test.cs

@@ -13,11 +13,11 @@ public class NDArrayStdTest
         [TestMethod]
         public void StdTest()
         {
-            var np = new NDArray(typeof(double)).arange(4).reshape(2,2).MakeGeneric<double>();
+            var nd1 = new NDArray(typeof(double)).arange(4).reshape(2,2).MakeGeneric<double>();
 
-            //Assert.IsTrue(Enumerable.SequenceEqual(np.s .Data, new double[] { 1.1180339887498949 }));
-            // Assert.IsTrue(Enumerable.SequenceEqual(np.Std(0).Data, new double[] { 1, 1 }));
-            // Assert.IsTrue(Enumerable.SequenceEqual(np.Std(1).Data, new double[] { 0.5, 3.5 }));
+            Assert.IsTrue(Enumerable.SequenceEqual(nd1.std().Data<double>(), new double[] { 1.1180339887498949 }));
+            Assert.IsTrue(Enumerable.SequenceEqual(nd1.std(0).Data<double>(), new double[] { 1, 1 }));
+            Assert.IsTrue(Enumerable.SequenceEqual(nd1.std(1).Data<double>(), new double[] { 0.5, 0.5 }));
         }
     }
 }

test/NumSharp.UnitTest/NumSharp.UnitTest.csproj

@@ -22,8 +22,6 @@
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <DebugType>full</DebugType>
-    <DebugSymbols>true</DebugSymbols>
   </PropertyGroup>
 
   <ItemGroup Condition="$([System.Text.RegularExpressions.Regex]::IsMatch('$(TargetFramework)', '^net\d'))">