Determine the unique values in a CV matrix

get_unique_values.cpp

// function declaration
std::vector<float> unique(const cv::Mat& input, bool sort);

// the actual function
std::vector<float> unique(const cv::Mat& input, bool sort)
{
  if (input.channels() > 1 || input.type() != CV_32F)
  {
    std::cerr << "unique !!! Only works with CV_32F 1-channel Mat" << std::endl;
    return std::vector<float>();
  }

  std::vector<float> out;
  for (int y = 0; y < input.rows; ++y)
  {
    const float* row_ptr = input.ptr<float>(y);
    for (int x = 0; x < input.cols; ++x)
    {
      float value = row_ptr[x];

      if ( std::find(out.begin(), out.end(), value) == out.end() )
        out.push_back(value);
    }
  }

  if (sort)
    std::sort(out.begin(), out.end());

  return out;
}


// previously defined
cv::Mat cv_matrix;

// function usage
std::vector<float> unik = unique(cv_matrix, true);
for (unsigned int i = 0; i < unik.size(); i++)
{
  std::cout << unik[i] << " ";
}