StreamAlignedBatcher.h

Go to the documentation of this file.

#pragma once
#include <vector>
#include <random>
#include <cstring>
#include <stdexcept>

 
namespace Deep
{
    class StreamAlignedBatcher
    {
    public:
        StreamAlignedBatcher(const float *X, const float *Y, const int *labels,
                              size_t numSamples, size_t xStride, size_t yStride,
                              int numClasses, int perClass, unsigned seed = 42);

        size_t NumBatchesPerEpoch() const noexcept;

        void GetBatch(float *X_out, float *Y_out, int *labels_out) noexcept;

        int GetBatchSize() const noexcept { return numClasses * perClass; }
        int GetPerClass() const noexcept { return perClass; }
        int GetNumClasses() const noexcept { return numClasses; }
        size_t GetXStride() const noexcept { return xStride; }
        size_t GetYStride() const noexcept { return yStride; }
 
    private:
        const float *X;
        const float *Y;
        const int *labels;
        size_t numSamples;
        size_t xStride;
        size_t yStride;
        int numClasses;
        int perClass;
        std::mt19937 rng;
 
        std::vector<std::vector<size_t>> classIndices; // per-class list of global row indices
        std::vector<size_t> pointers;                  // current read position within each class's list
 
        void ReshuffleClass(int c) noexcept;

        std::vector<size_t> NextClassSlice(int c, int n) noexcept;
    };
}