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;

}

}

}