std::strided_slice - cppreference.com (original) (raw)

#include #include   template <typename View, typename O = int, typename E = int, typename S = int> requires (View::extents_type::rank() == 1) void print_sliced_view(View v, std::strided_slice<O, E, S> s) { using index_type = View::index_type; auto subview = std::submdspan(v, s); const auto& submap = subview.mapping();   std::print("["); bool uses_comma = false; for (index_type i = 0; i != subview.extent(0); ++i) { if (uses_comma) std::print(", "); std::print("{}", subview[i]); uses_comma = true; } uses_comma = false; std::print("] extracted from indices ["); for (index_type i = 0; i != subview.extent(0); ++i) { if (uses_comma) std::print(", "); std::print("{}", submap(i) + s.offset); uses_comma = true; } std::println("]"); }   int main() { static constexpr char letters[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' }; constexpr std::mdspan md(letters, 26); print_sliced_view(md, {.offset = 0, .extent = 10, .stride = 1}); print_sliced_view(md, {.offset = 2, .extent = 10, .stride = 1}); print_sliced_view(md, {.offset = 0, .extent = 5, .stride = 1}); print_sliced_view(md, {.offset = 2, .extent = 5, .stride = 1}); print_sliced_view(md, {.offset = 0, .extent = 10, .stride = 2}); print_sliced_view(md, {.offset = 2, .extent = 10, .stride = 3}); print_sliced_view(md, {.offset = 0, .extent = 15, .stride = 5}); print_sliced_view(md, {.offset = 6, .extent = 15, .stride = 5}); }

[A, B, C, D, E, F, G, H, I, J] extracted from indices [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [C, D, E, F, G, H, I, J, K, L] extracted from indices [2, 3, 4, 5, 6, 7, 8, 9, 10, 11] [A, B, C, D, E] extracted from indices [0, 1, 2, 3, 4] [C, D, E, F, G] extracted from indices [2, 3, 4, 5, 6] [A, C, E, G, I] extracted from indices [0, 2, 4, 6, 8] [C, F, I, L] extracted from indices [2, 5, 8, 11] [A, F, K] extracted from indices [0, 5, 10] [G, L, Q] extracted from indices [6, 11, 16]