sort_impl.hpp

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#ifndef MLPACK_METHODS_AUGMENTED_TASKS_SORT_IMPL_HPP
#define MLPACK_METHODS_AUGMENTED_TASKS_SORT_IMPL_HPP

#include "sort.hpp"

namespace mlpack {
namespace ann /* Artificial Neural Network */ {
namespace augmented /* Augmented neural network */ {
namespace tasks /* Task utilities for augmented */ {

SortTask::SortTask(const size_t maxLength,
                   const size_t bitLen,
                   bool addSeparator)
  : maxLength(maxLength), bitLen(bitLen), addSeparator(addSeparator)
{
  if (maxLength <= 1)
  {
    std::ostringstream oss;
    oss << "SortTask::SortTask(): maximum sequence length ("
        << maxLength << ") "
        << "should be at least 2!"
        << std::endl;
    throw std::invalid_argument(oss.str());
  }
  if (bitLen <= 0)
  {
    std::ostringstream oss;
    oss << "SortTask::SortTask(): binary length (" << bitLen << ") "
        << "is not positive!"
        << std::endl;
    throw std::invalid_argument(oss.str());
  }
}

void SortTask::Generate(arma::field<arma::mat>& input,
                        arma::field<arma::mat>& labels,
                        const size_t batchSize,
                        bool fixedLength) const
{
  input = arma::field<arma::mat>(batchSize);
  labels = arma::field<arma::mat>(batchSize);
  size_t size = maxLength;
  for (size_t i = 0; i < batchSize; ++i)
  {
    if (!fixedLength)
    {
      // Generate random uniform length from [2..maxLength].
      size = mlpack::math::RandInt(2, maxLength+1);
    }
    input(i) = arma::randi<arma::mat>(bitLen, size, arma::distr_param(0, 1));
    arma::mat itemAns(bitLen, size);
    arma::colvec vals(size);
    for (size_t j = 0; j < size; ++j)
    {
      int val = 0;
      for (size_t k = 0; k < bitLen; ++k)
      {
        val <<= 1;
        val += input(i).at(k, j);
      }
      vals[j] = val;
    }
    arma::uvec indices = arma::sort_index(vals);
    for (size_t j = 0; j < size; ++j)
    {
      itemAns.col(j) = input(i).col(indices.at(j));
    }
    labels(i) = itemAns;
    input(i).reshape(input(i).n_elem, 1);
    if (addSeparator)
    {
      arma::mat sepInput = arma::zeros(input(i).n_elem + size, 1);
      size_t ptr = 0, origPtr = 0;
      for (size_t j = 0; j < size; ++j)
      {
        sepInput.rows(ptr, ptr + bitLen - 1) =
          input(i).rows(origPtr, origPtr + bitLen - 1);
        ptr += bitLen;
        origPtr += bitLen;
        sepInput.at(ptr, 0) = 0.5;
        ++ptr;
      }
      input(i) = sepInput;
    }
    labels(i).reshape(labels(i).n_elem, 1);
  }
}

void SortTask::Generate(arma::mat& input,
                        arma::mat& labels,
                        const size_t batchSize) const
{
  arma::field<arma::mat> fieldInput, fieldLabels;
  Generate(fieldInput, fieldLabels, batchSize, true);
  size_t inputRows = fieldInput(0).n_rows;
  size_t labelRows = fieldLabels(0).n_rows;
  size_t cols = batchSize;
  input = arma::zeros(inputRows, cols);
  labels = arma::zeros(labelRows, cols);
  for (size_t i = 0; i < cols; ++i)
  {
    input.col(i) = fieldInput.at(i);
    labels.col(i) = fieldLabels.at(i);
  }
}

} // namespace tasks
} // namespace augmented
} // namespace ann
} // namespace mlpack
#endif