rankFilter1d.hpp

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#pragma once
 
#include "NumCpp/Core/Slice.hpp"
#include "NumCpp/Core/Types.hpp"
#include "NumCpp/Filter/Boundaries/Boundaries1d/addBoundary1d.hpp"
#include "NumCpp/Filter/Boundaries/Boundary.hpp"
#include "NumCpp/Functions/sort.hpp"
#include "NumCpp/NdArray.hpp"
 
namespace nc::filter
{
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<dtype> rankFilter1d(const NdArray<dtype>& inImageArray,
                                uint32                inSize,
                                uint8                 inRank,
                                Boundary              inBoundaryType  = Boundary::REFLECT,
                                dtype                 inConstantValue = 0)
    {
        if (inRank >= inSize)
        {
            THROW_INVALID_ARGUMENT_ERROR("rank not within filter footprint size.");
        }
 
        NdArray<dtype> arrayWithBoundary =
            boundary::addBoundary1d(inImageArray, inBoundaryType, inSize, inConstantValue);
        NdArray<dtype> output(1, inImageArray.size());
 
        const uint32 boundarySize = inSize / 2; // integer division
        const uint32 endPoint     = boundarySize + inImageArray.size();
 
        for (uint32 i = boundarySize; i < endPoint; ++i)
        {
            NdArray<dtype> window = arrayWithBoundary[Slice(i - boundarySize, i + boundarySize + 1)];
 
            output[i - boundarySize] = sort(window)[inRank];
        }
 
        return output;
    }
} // namespace nc::filter