mean.hpp

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#pragma once
 
#include <complex>
#include <numeric>
 
#include "NumCpp/Core/Internal/StaticAsserts.hpp"
#include "NumCpp/Core/Shape.hpp"
#include "NumCpp/Core/Types.hpp"
#include "NumCpp/NdArray.hpp"
 
namespace nc
{
    //===========================================================================
    // Method Description:
    template<typename dtype>
    NdArray<double> mean(const NdArray<dtype>& inArray, Axis inAxis = Axis::NONE)
    {
        STATIC_ASSERT_ARITHMETIC(dtype);
 
        switch (inAxis)
        {
            case Axis::NONE:
            {
                auto            sum         = std::accumulate(inArray.cbegin(), inArray.cend(), 0.);
                NdArray<double> returnArray = { sum /= static_cast<double>(inArray.size()) };
 
                return returnArray;
            }
            case Axis::COL:
            {
                NdArray<double> returnArray(1, inArray.numRows());
                for (uint32 row = 0; row < inArray.numRows(); ++row)
                {
                    auto sum            = std::accumulate(inArray.cbegin(row), inArray.cend(row), 0.);
                    returnArray(0, row) = sum / static_cast<double>(inArray.numCols());
                }
 
                return returnArray;
            }
            case Axis::ROW:
            {
                return mean(inArray.transpose(), Axis::COL);
            }
            default:
            {
                THROW_INVALID_ARGUMENT_ERROR("Unimplemented axis type.");
                return {};
            }
        }
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<std::complex<double>> mean(const NdArray<std::complex<dtype>>& inArray, Axis inAxis = Axis::NONE)
    {
        STATIC_ASSERT_ARITHMETIC(dtype);
 
        switch (inAxis)
        {
            case Axis::NONE:
            {
                auto sum = std::accumulate(inArray.cbegin(), inArray.cend(), std::complex<double>(0.));
                NdArray<std::complex<double>> returnArray = { sum /= std::complex<double>(inArray.size()) };
 
                return returnArray;
            }
            case Axis::COL:
            {
                NdArray<std::complex<double>> returnArray(1, inArray.numRows());
                for (uint32 row = 0; row < inArray.numRows(); ++row)
                {
                    auto sum = std::accumulate(inArray.cbegin(row), inArray.cend(row), std::complex<double>(0.));
                    returnArray(0, row) = sum / std::complex<double>(inArray.numCols());
                }
 
                return returnArray;
            }
            case Axis::ROW:
            {
                NdArray<std::complex<double>> transposedArray = inArray.transpose();
                NdArray<std::complex<double>> returnArray(1, transposedArray.numRows());
                for (uint32 row = 0; row < transposedArray.numRows(); ++row)
                {
                    auto sum            = std::accumulate(transposedArray.cbegin(row),
                                               transposedArray.cend(row),
                                               std::complex<double>(0.));
                    returnArray(0, row) = sum / std::complex<double>(transposedArray.numCols());
                }
 
                return returnArray;
            }
            default:
            {
                THROW_INVALID_ARGUMENT_ERROR("Unimplemented axis type.");
                return {}; // get rid of compiler warning
            }
        }
    }
} // namespace nc