Function extract_contour

ops/cpp_modules/src/cpp_modules.cpp:521–558

std::tuple<py::array_t<int>, py::array_t<int>> extract_contour(py::array_t<int> idx_map) {
    // input array
    py::buffer_info im_buf = idx_map.request();
    int *im_ptr = (int *) im_buf.ptr;
    int h = im_buf.shape[0];
    int w = im_buf.shape[1];

    // return array
    auto contour_map = py::array_t<int>(h * w);
    py::buffer_info cm_buf = contour_map.request();
    int *cm_ptr = (int *) cm_buf.ptr;

    vector<int> idx_sequence_vec;
    for (int h_i = 0; h_i < h; h_i++){
        idx_sequence_vec.push_back(im_ptr[h_i * w]);
        cm_ptr[h_i * w] = 1;
        for (int w_i = 1; w_i < w; w_i++)
            if (im_ptr[h_i * w + w_i] - im_ptr[h_i * w + w_i - 1] != 0){
                idx_sequence_vec.push_back(im_ptr[h_i * w + w_i]);
                cm_ptr[h_i * w + w_i] = 1;
            }
            else{
                cm_ptr[h_i * w + w_i] = 0;
            }
    }

    // return array
    int seq_size = idx_sequence_vec.size();
    auto idx_sequence = py::array_t<int>(seq_size);
    py::buffer_info is_buf = idx_sequence.request();
    int *is_ptr = (int *) is_buf.ptr;
    for (int i = 0; i < seq_size; i++){
        is_ptr[i] = idx_sequence_vec[i];
    }

    contour_map.resize({h, w});
    return std::make_tuple(contour_map, idx_sequence);
}


py::array_t<int> recover_map(py::array_t<int> contour_map, py::array_t<int> idx_sequence) {