Refactor of pairwise_linestring_distance to use `multilinestring_ra…

…nge`, adds support to multilinestring distance (#755)

Note, this is the first part of `pairwise_linestring_distance` refactoring, part 1 of PR: #753

Depends on #752 

Contributes to #706, #703

Closes #745

Authors:
  - Michael Wang (https://github.com/isVoid)

Approvers:
  - H. Thomson Comer (https://github.com/thomcom)
  - Mark Harris (https://github.com/harrism)

URL: #755

cpp/benchmarks/pairwise_linestring_distance.cu

@@ -20,6 +20,7 @@
 #include <cuspatial/detail/iterator.hpp>
 #include <cuspatial/experimental/iterator_factory.cuh>
 #include <cuspatial/experimental/linestring_distance.cuh>
+#include <cuspatial/experimental/ranges/multilinestring_range.cuh>
 #include <cuspatial/vec_2d.hpp>
 
 #include <rmm/device_vector.hpp>
@@ -104,13 +105,21 @@ void pairwise_linestring_distance_benchmark(nvbench::state& state, nvbench::type
   auto [ls2, ls2_offset] =
     generate_linestring<T>(num_string_pairs, num_segments_per_string, 1, {100, 100});
 
-  auto ls1_offset_begin = ls1_offset.begin();
-  auto ls2_offset_begin = ls2_offset.begin();
-  auto ls1_points_begin = ls1.begin();
-  auto ls2_points_begin = ls2.begin();
-  auto distances        = rmm::device_vector<T>(ls1.size());
-  auto out_it           = distances.begin();
-
+  auto distances = rmm::device_vector<T>(ls1.size());
+  auto out_it    = distances.begin();
+
+  auto multilinestrings1  = make_multilinestring_range(1,
+                                                      thrust::make_counting_iterator(0),
+                                                      num_string_pairs,
+                                                      ls1_offset.begin(),
+                                                      ls1.size(),
+                                                      ls1.begin());
+  auto multilinestrings2  = make_multilinestring_range(1,
+                                                      thrust::make_counting_iterator(0),
+                                                      num_string_pairs,
+                                                      ls2_offset.begin(),
+                                                      ls2.size(),
+                                                      ls2.begin());
   auto const total_points = ls1.size() + ls2.size();
 
   state.add_element_count(num_string_pairs, "LineStringPairs");
@@ -120,22 +129,8 @@ void pairwise_linestring_distance_benchmark(nvbench::state& state, nvbench::type
   state.add_global_memory_writes<T>(num_string_pairs);
 
   state.exec(nvbench::exec_tag::sync,
-             [&ls1_offset_begin,
-              &num_string_pairs,
-              &ls1_points_begin,
-              ls1_size = ls1.size(),
-              &ls2_offset_begin,
-              &ls2_points_begin,
-              ls2_size = ls2.size(),
-              &out_it](nvbench::launch& launch) {
-               pairwise_linestring_distance(ls1_offset_begin,
-                                            ls1_offset_begin + num_string_pairs,
-                                            ls1_points_begin,
-                                            ls1_points_begin + ls1_size,
-                                            ls2_offset_begin,
-                                            ls2_points_begin,
-                                            ls2_points_begin + ls2_size,
-                                            out_it);
+             [&multilinestrings1, &multilinestrings2, &out_it](nvbench::launch& launch) {
+               pairwise_linestring_distance(multilinestrings1, multilinestrings2, out_it);
              });
 }
 

cpp/include/cuspatial/detail/iterator.hpp

@@ -15,17 +15,16 @@
  */
 
 #pragma once
-
-#include <cudf/types.hpp>
+#include <cuspatial/cuda_utils.hpp>
 
 #include <thrust/iterator/counting_iterator.h>
 #include <thrust/iterator/transform_iterator.h>
 
 namespace cuspatial {
 namespace detail {
 
-template <typename UnaryFunction>
-inline auto make_counting_transform_iterator(cudf::size_type start, UnaryFunction f)
+template <typename IndexType, typename UnaryFunction>
+inline CUSPATIAL_HOST_DEVICE auto make_counting_transform_iterator(IndexType start, UnaryFunction f)
 {
   return thrust::make_transform_iterator(thrust::make_counting_iterator(start), f);
 }

cpp/include/cuspatial/detail/utility/linestring.cuh

@@ -92,10 +92,9 @@ __forceinline__ T __device__ segment_distance_no_intersect_or_colinear(vec_2d<T>
                                                                        vec_2d<T> const& c,
                                                                        vec_2d<T> const& d)
 {
-  auto dist_sqr = std::min(std::min(point_to_segment_distance_squared(a, c, d),
-                                    point_to_segment_distance_squared(b, c, d)),
-                           std::min(point_to_segment_distance_squared(c, a, b),
-                                    point_to_segment_distance_squared(d, a, b)));
+  auto dist_sqr = min(
+    min(point_to_segment_distance_squared(a, c, d), point_to_segment_distance_squared(b, c, d)),
+    min(point_to_segment_distance_squared(c, a, b), point_to_segment_distance_squared(d, a, b)));
   return dist_sqr;
 }
 

cpp/include/cuspatial/experimental/detail/geometry/linestring_ref.cuh

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2022, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+#include <cuspatial/cuda_utils.hpp>
+#include <cuspatial/detail/iterator.hpp>
+#include <cuspatial/traits.hpp>
+
+#include <thrust/iterator/zip_iterator.h>
+#include <thrust/tuple.h>
+
+namespace cuspatial {
+
+template <typename VecIterator>
+struct to_segment_functor {
+  using element_t       = iterator_vec_base_type<VecIterator>;
+  using difference_type = typename thrust::iterator_difference<VecIterator>::type;
+  VecIterator _point_begin;
+
+  CUSPATIAL_HOST_DEVICE
+  to_segment_functor(VecIterator point_begin) : _point_begin(point_begin) {}
+
+  CUSPATIAL_HOST_DEVICE
+  thrust::pair<vec_2d<element_t>, vec_2d<element_t>> operator()(difference_type i)
+  {
+    return {_point_begin[i], _point_begin[i + 1]};
+  }
+};
+
+template <typename VecIterator>
+CUSPATIAL_HOST_DEVICE linestring_ref<VecIterator>::linestring_ref(VecIterator begin,
+                                                                  VecIterator end)
+  : _point_begin(begin), _point_end(end)
+{
+  using T = iterator_vec_base_type<VecIterator>;
+  static_assert(is_same<vec_2d<T>, iterator_value_type<VecIterator>>(), "must be vec2d type");
+}
+
+template <typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto linestring_ref<VecIterator>::num_segments() const
+{
+  // The number of segment equals the number of points minus 1. And the number of points
+  // is thrust::distance(_point_begin, _point_end) - 1.
+  return thrust::distance(_point_begin, _point_end) - 1;
+}
+
+template <typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto linestring_ref<VecIterator>::segment_begin() const
+{
+  return detail::make_counting_transform_iterator(0, to_segment_functor{_point_begin});
+}
+
+template <typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto linestring_ref<VecIterator>::segment_end() const
+{
+  return segment_begin() + num_segments();
+}
+
+}  // namespace cuspatial

cpp/include/cuspatial/experimental/detail/geometry_collection/multilinestring_ref.cuh

@@ -0,0 +1,70 @@
+#pragma once
+
+#include "cuspatial/cuda_utils.hpp"
+#include <cuspatial/detail/iterator.hpp>
+#include <cuspatial/experimental/geometry/linestring_ref.cuh>
+
+#include <thrust/iterator/transform_iterator.h>
+
+namespace cuspatial {
+
+template <typename PartIterator, typename VecIterator>
+struct to_linestring_functor {
+  using difference_type = typename thrust::iterator_difference<PartIterator>::type;
+  PartIterator part_begin;
+  VecIterator point_begin;
+
+  CUSPATIAL_HOST_DEVICE
+  to_linestring_functor(PartIterator part_begin, VecIterator point_begin)
+    : part_begin(part_begin), point_begin(point_begin)
+  {
+  }
+
+  CUSPATIAL_HOST_DEVICE auto operator()(difference_type i)
+  {
+    return linestring_ref{point_begin + part_begin[i], point_begin + part_begin[i + 1]};
+  }
+};
+
+template <typename PartIterator, typename VecIterator>
+class multilinestring_ref;
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE multilinestring_ref<PartIterator, VecIterator>::multilinestring_ref(
+  PartIterator part_begin, PartIterator part_end, VecIterator point_begin, VecIterator point_end)
+  : _part_begin(part_begin), _part_end(part_end), _point_begin(point_begin), _point_end(point_end)
+{
+}
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto multilinestring_ref<PartIterator, VecIterator>::num_linestrings() const
+{
+  return thrust::distance(_part_begin, _part_end) - 1;
+}
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto multilinestring_ref<PartIterator, VecIterator>::part_begin() const
+{
+  return detail::make_counting_transform_iterator(0,
+                                                  to_linestring_functor{_part_begin, _point_begin});
+}
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto multilinestring_ref<PartIterator, VecIterator>::part_end() const
+{
+  return part_begin() + num_linestrings();
+}
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto multilinestring_ref<PartIterator, VecIterator>::point_begin() const
+{
+  return _point_begin;
+}
+
+template <typename PartIterator, typename VecIterator>
+CUSPATIAL_HOST_DEVICE auto multilinestring_ref<PartIterator, VecIterator>::point_end() const
+{
+  return _point_end;
+}
+
+}  // namespace cuspatial