row_stack.hpp

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#pragma once
 
#include <initializer_list>
#include <string>
#include <vector>
 
#include "NumCpp/Core/Internal/Error.hpp"
#include "NumCpp/Core/Shape.hpp"
#include "NumCpp/Core/Types.hpp"
#include "NumCpp/NdArray.hpp"
 
namespace nc
{
    namespace detail
    {
        //============================================================================
        // Method Description:
        template<typename dtype, typename Iterator>
        NdArray<dtype> row_stack(Iterator begin, Iterator end)
        {
            // first loop through to calculate the final size of the array
            Shape finalShape;
            auto  iter = begin;
            while (iter != end)
            {
                const auto& ndarray = *iter++;
                if (ndarray.shape().isnull())
                {
                    continue;
                }
 
                if (finalShape.isnull())
                {
                    finalShape = ndarray.shape();
                }
                else if (ndarray.shape().cols != finalShape.cols)
                {
                    THROW_INVALID_ARGUMENT_ERROR("input arrays must have the same number of columns.");
                }
                else
                {
                    finalShape.rows += ndarray.shape().rows;
                }
            }
 
            // now that we know the final size, contruct the output array
            NdArray<dtype> returnArray(finalShape);
            uint32         rowStart = 0;
            iter                    = begin;
            while (iter != end)
            {
                const auto& ndarray  = *iter++;
                const Shape theShape = ndarray.shape();
                for (uint32 row = 0; row < theShape.rows; ++row)
                {
                    for (uint32 col = 0; col < theShape.cols; ++col)
                    {
                        returnArray(rowStart + row, col) = ndarray(row, col);
                    }
                }
                rowStart += theShape.rows;
            }
 
            return returnArray;
        }
    } // namespace detail
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<dtype> row_stack(const std::initializer_list<NdArray<dtype>>& inArrayList)
    {
        return detail::row_stack<dtype>(inArrayList.begin(), inArrayList.end());
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<dtype> row_stack(const std::vector<NdArray<dtype>>& inArrayList)
    {
        return detail::row_stack<dtype>(inArrayList.begin(), inArrayList.end());
    }
} // namespace nc