v0.8.0 Patch (#29)

Added array traits to support default point types. Documentation and examples updated. Map traits return type fix. Added SplitterMidpoint unit tests.
Jaybro · Jul 3, 2023 · 62e457b · 62e457b
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diff --git a/README.md b/README.md
@@ -27,28 +27,38 @@ Available under the [MIT](https://en.wikipedia.org/wiki/MIT_License) license.
 
 # Capabilities
 
-* KdTree:
-  * Nearest neighbor, approximate nearest neighbor, radius, box, and customizable nearest neighbor searches.
-  * Multiple tree splitting rules: `kLongestMedian`, `kMidpoint` and `kSlidingMidpoint`.
-  * [Metrics](https://en.wikipedia.org/wiki/Metric_(mathematics)):
-    * Support for topological spaces with identifications. E.g., points on the circle `[-pi, pi]`.
-    * Available metrics: `L1`, `L2Squared`, `SO2`, and `SE2Squared`. Metrics can be customized.
-  * Compile time and run time known dimensions.
-  * Static tree builds.
-  * Thread safe queries.
-* PicoTree can interface with different types of points or point sets through traits classes. These can be custom implementations or one of the `pico_tree::PointTraits<>` and `pico_tree::SpaceTraits<>` classes provided by this library. There is default support for the following data types:
+KdTree:
+* Nearest neighbor, approximate nearest neighbor, radius, box, and customizable nearest neighbor searches.
+* [Metrics](https://en.wikipedia.org/wiki/Metric_(mathematics)):
+  * Support for topological spaces with identifications. E.g., points on the circle `[-pi, pi]`.
+  * Available metrics: `L1`, `L2Squared`, `SO2`, and `SE2Squared`. Metrics can be customized.
+* Multiple tree splitting rules: `kLongestMedian`, `kMidpoint` and `kSlidingMidpoint`.
+* Compile time and run time known dimensions.
+* Static tree builds.
+* Thread safe queries.
+
+PicoTree can interface with different types of points and point sets through traits classes. These can be custom implementations or one of the `pico_tree::SpaceTraits<>` and `pico_tree::PointTraits<>` classes provided by this library.
+* Space type support:
   * `std::vector<PointType>`.
-    * A specialization of `pico_tree::PointTraits<>` is required for each `PointType`. There are traits available for Eigen and OpenCV point types.
-  * `pico_tree::SpaceMap<PointType>` and `pico_tree::PointMap<>`.
-    * These classes allow interfacing with raw pointers. It is assumed that points and their coordinates are laid out contiguously in memory.
-  * `Eigen::Matrix` and `Eigen::Map<Eigen::Matrix>`.
+  * `pico_tree::SpaceMap<PointType>`.
+  * `Eigen::Matrix<>` and `Eigen::Map<Eigen::Matrix<>>`.
   * `cv::Mat`.
+* Point type support:
+  * Fixed size arrays and `std::array<>`.
+  * `pico_tree::PointMap<>`.
+  * `Eigen::Vector<>` and `Eigen::Map<Eigen::Vector<>>`.
+  * `cv::Vec<>`.
+* `pico_tree::SpaceMap<PointType>` and `pico_tree::PointMap<>` allow interfacing with dynamic size arrays. It is assumed that points and their coordinates are laid out contiguously in memory.
 
 # Examples
 
-* [Minimal working example](./examples/kd_tree/kd_tree_minimal.cpp) using an std::vector of points.
-* Creating [traits](./examples/kd_tree/kd_tree_traits.cpp) classes for a custom point and point set.
-* Using the KdTree's [search](./examples/kd_tree/kd_tree_search.cpp) options and creating a custom search visitor.
+* [Minimal working example](./examples/kd_tree/kd_tree_minimal.cpp) using an `std::vector<>` of points.
+* [Creating a KdTree](./examples/kd_tree/kd_tree_creation.cpp) and taking the input by value or reference.
+* Using the KdTree's [search](./examples/kd_tree/kd_tree_search.cpp) capabilities.
+* Working with [dynamic size arrays](./examples/kd_tree/kd_tree_dynamic_arrays.cpp).
+* Supporting a [custom point type](./examples/kd_tree/kd_tree_custom_point_type.cpp).
+* Supporting a [custom space type](./examples/kd_tree/kd_tree_custom_space_type.cpp).
+* Creating a [custom search visitor](./examples/kd_tree/kd_tree_custom_search_visitor.cpp).
 * Support for [Eigen](./examples/eigen/eigen.cpp) and [OpenCV](./examples/opencv/opencv.cpp) data types.
 * How to use the [KdTree with Python](./examples/python/kd_tree.py).
 

diff --git a/examples/eigen/eigen.cpp b/examples/eigen/eigen.cpp
@@ -3,37 +3,31 @@
 #include <pico_tree/kd_tree.hpp>
 #include <pico_tree/vector_traits.hpp>
 
-// NOTES:
-
 // Because we use C++17 there is no need to take care of memory alignment:
 // https://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html
 // https://eigen.tuxfamily.org/dox-devel/group__TopicStlContainers.html
 
-// The Eigen example is not a performance benchmark. So don't take the "elapsed
-// time" numbers too seriously.
-
-using Index = int;
-
 template <typename Point>
-using PointsMapCm = Eigen::Map<Eigen::Matrix<
+using PointsMapColMajor = Eigen::Map<Eigen::Matrix<
     typename Point::Scalar,
     Point::RowsAtCompileTime,
     Eigen::Dynamic>>;
 
 template <typename Point>
-using PointsMapRm = Eigen::Map<Eigen::Matrix<
+using PointsMapRowMajor = Eigen::Map<Eigen::Matrix<
     typename Point::Scalar,
     Eigen::Dynamic,
     Point::ColsAtCompileTime,
     Eigen::RowMajor>>;
 
 std::size_t const kRunCount = 1024 * 1024;
-int const kNumPoints = 1024 * 1024 * 2;
+std::size_t const kNumPoints = 1024 * 1024 * 2;
 float const kArea = 1000.0;
-Index const kMaxLeafCount = 16;
+std::size_t const kMaxLeafCount = 16;
 
 template <typename PointX>
-std::vector<PointX> GenerateRandomEigenN(int n, typename PointX::Scalar size) {
+std::vector<PointX> GenerateRandomEigenN(
+    std::size_t n, typename PointX::Scalar size) {
   std::vector<PointX> random(n);
   for (auto& p : random) {
     p = PointX::Random() * size / typename PointX::Scalar(2.0);
@@ -46,10 +40,12 @@ std::vector<PointX> GenerateRandomEigenN(int n, typename PointX::Scalar size) {
 // neighbors.
 void BasicVector() {
   using PointX = Eigen::Vector2f;
-  using Scalar = typename PointX::Scalar;
+  using KdTree = pico_tree::KdTree<std::vector<PointX>>;
+  using Scalar = typename KdTree::ScalarType;
+  using Index = typename KdTree::IndexType;
 
-  // Including <pico_tree/eigen.hpp> provides support for Eigen types with
-  // std::vector.
+  // Including <pico_tree/eigen3_traits.hpp> provides support for Eigen types
+  // with std::vector.
   pico_tree::KdTree<std::vector<PointX>> tree(
       GenerateRandomEigenN<PointX>(kNumPoints, kArea), kMaxLeafCount);
 
@@ -64,95 +60,75 @@ void BasicVector() {
 
 // Creates a KdTree from an Eigen::Matrix<> and searches for nearest neighbors.
 void BasicMatrix() {
+  using KdTree = pico_tree::KdTree<Eigen::Matrix3Xf>;
+  using Neighbor = typename KdTree::NeighborType;
   using Scalar = typename Eigen::Matrix3Xf::Scalar;
   constexpr int Dim = Eigen::Matrix3Xf::RowsAtCompileTime;
 
-  Eigen::Vector3f p = Eigen::Vector3f::Random() * kArea / Scalar(2.0);
-
-  // The KdTree takes the matrix by value. Prevent a copy by:
-  // * Using a move.
-  // * Creating an Eigen::Map<>.
-  // * Wrap with an std::reference_wrapper<>.
-  {
-    pico_tree::KdTree<Eigen::Matrix3Xf> tree(
-        Eigen::Matrix3Xf::Random(Dim, kNumPoints) * kArea / Scalar(2.0),
-        kMaxLeafCount);
-
-    pico_tree::Neighbor<Index, Scalar> nn;
-    ScopedTimer t("pico_tree eigen val", kRunCount);
-    for (std::size_t i = 0; i < kRunCount; ++i) {
-      tree.SearchNn(p, nn);
-    }
-  }
-
-  {
-    Eigen::Matrix3Xf matrix =
-        Eigen::Matrix3Xf::Random(Dim, kNumPoints) * kArea / Scalar(2.0);
+  KdTree tree(
+      Eigen::Matrix3Xf::Random(Dim, kNumPoints) * kArea / Scalar(2.0),
+      kMaxLeafCount);
 
-    pico_tree::KdTree<std::reference_wrapper<Eigen::Matrix3Xf>> tree(
-        matrix, kMaxLeafCount);
-
-    pico_tree::Neighbor<Index, Scalar> nn;
-    ScopedTimer t("pico_tree eigen ref", kRunCount);
-    for (std::size_t i = 0; i < kRunCount; ++i) {
-      tree.SearchNn(p, nn);
-    }
+  Eigen::Vector3f p = Eigen::Vector3f::Random() * kArea / Scalar(2.0);
+  Neighbor nn;
+  ScopedTimer t("pico_tree eigen matrix", kRunCount);
+  for (std::size_t i = 0; i < kRunCount; ++i) {
+    tree.SearchNn(p, nn);
   }
 }
 
 // Creates a KdTree from a col-major matrix. The matrix maps an
 // std::vector<Eigen::Vector3f>.
-void VectorMapColMajor() {
+void ColMajorSupport() {
   using PointX = Eigen::Vector3f;
+  using Map = PointsMapColMajor<PointX>;
+  using KdTree = pico_tree::KdTree<Map>;
+  using Neighbor = typename KdTree::NeighborType;
   using Scalar = typename PointX::Scalar;
   constexpr int Dim = PointX::RowsAtCompileTime;
-  using Map = PointsMapCm<PointX>;
 
   auto points = GenerateRandomEigenN<PointX>(kNumPoints, kArea);
   PointX p = PointX::Random() * kArea / Scalar(2.0);
 
   std::cout << "Eigen RowMajor: " << Map::IsRowMajor << std::endl;
-  {
-    pico_tree::KdTree<Map> tree(
-        Map(points.data()->data(), Dim, points.size()), kMaxLeafCount);
-
-    std::vector<pico_tree::Neighbor<Index, Scalar>> knn;
-    ScopedTimer t("pico_tree deflt l2", kRunCount);
-    for (std::size_t i = 0; i < kRunCount; ++i) {
-      tree.SearchKnn(p, 1, knn);
-    }
+
+  KdTree tree(Map(points.data()->data(), Dim, points.size()), kMaxLeafCount);
+
+  std::vector<Neighbor> knn;
+  ScopedTimer t("pico_tree col major", kRunCount);
+  for (std::size_t i = 0; i < kRunCount; ++i) {
+    tree.SearchKnn(p, 1, knn);
   }
 }
 
 // Creates a KdTree from a row-major matrix. The matrix maps an
 // std::vector<Eigen::RowVector3f>.
-void VectorMapRowMajor() {
+void RowMajorSupport() {
   using PointX = Eigen::RowVector3f;
+  using Map = PointsMapRowMajor<PointX>;
+  using KdTree = pico_tree::KdTree<Map>;
+  using Neighbor = typename KdTree::NeighborType;
   using Scalar = typename PointX::Scalar;
   constexpr int Dim = PointX::ColsAtCompileTime;
-  using Map = PointsMapRm<PointX>;
 
   auto points = GenerateRandomEigenN<PointX>(kNumPoints, kArea);
   PointX p = PointX::Random() * kArea / Scalar(2.0);
 
   std::cout << "Eigen RowMajor: " << PointX::IsRowMajor << std::endl;
 
-  {
-    pico_tree::KdTree<Map> tree(
-        Map(points.data()->data(), points.size(), Dim), kMaxLeafCount);
+  KdTree tree(Map(points.data()->data(), points.size(), Dim), kMaxLeafCount);
 
-    std::vector<pico_tree::Neighbor<Index, Scalar>> knn;
-    ScopedTimer t("pico_tree deflt l2", kRunCount);
-    for (std::size_t i = 0; i < kRunCount; ++i) {
-      tree.SearchKnn(p, 1, knn);
-    }
+  std::vector<Neighbor> knn;
+  ScopedTimer t("pico_tree row major", kRunCount);
+  for (std::size_t i = 0; i < kRunCount; ++i) {
+    tree.SearchKnn(p, 1, knn);
   }
 }
 
 int main() {
   BasicVector();
   BasicMatrix();
-  VectorMapColMajor();
-  VectorMapRowMajor();
+  ColMajorSupport();
+  RowMajorSupport();
   return 0;
 }
diff --git a/examples/kd_tree/CMakeLists.txt b/examples/kd_tree/CMakeLists.txt
@@ -1,11 +1,19 @@
-add_executable(kd_tree_minimal kd_tree_minimal.cpp)
-set_default_target_properties(kd_tree_minimal)
-target_link_libraries(kd_tree_minimal PUBLIC PicoTree::PicoTree)
+function(add_demo_executable TARGET_NAME)
+    add_executable(${TARGET_NAME} ${TARGET_NAME}.cpp)
+    set_default_target_properties(${TARGET_NAME})
+    target_link_libraries(${TARGET_NAME} PRIVATE pico_toolshed)
+endfunction()
 
-add_executable(kd_tree_traits kd_tree_traits.cpp)
-set_default_target_properties(kd_tree_traits)
-target_link_libraries(kd_tree_traits PUBLIC PicoTree::PicoTree)
+add_demo_executable(kd_tree_minimal)
 
-add_executable(kd_tree_search kd_tree_search.cpp)
-set_default_target_properties(kd_tree_search)
-target_link_libraries(kd_tree_search PUBLIC pico_toolshed)
+add_demo_executable(kd_tree_creation)
+
+add_demo_executable(kd_tree_search)
+
+add_demo_executable(kd_tree_dynamic_arrays)
+
+add_demo_executable(kd_tree_custom_point_type)
+
+add_demo_executable(kd_tree_custom_space_type)
+
+add_demo_executable(kd_tree_custom_search_visitor)
diff --git a/examples/kd_tree/kd_tree_creation.cpp b/examples/kd_tree/kd_tree_creation.cpp
@@ -0,0 +1,79 @@
+#include <iostream>
+#include <pico_tree/array_traits.hpp>
+#include <pico_tree/kd_tree.hpp>
+#include <pico_tree/vector_traits.hpp>
+
+// This application demonstrates how a KdTree can take its input point set.
+// Although all of the examples use an std::vector<> as the input for building a
+// KdTree, they will work with any of the inputs supported by this library
+// (e.g., Eigen::Matrix<>).
+
+template <typename Tree>
+void QueryTree(Tree const& tree) {
+  float query[3] = {4.0f, 4.0f, 4.0f};
+  pico_tree::Neighbor<int, float> nn;
+  tree.SearchNn(query, nn);
+
+  std::cout << "Index closest point: " << nn.index << std::endl;
+}
+
+auto MakePointSet() {
+  std::vector<std::array<float, 3>> points{
+      {0.0f, 1.0f, 2.0f}, {3.0f, 4.0f, 5.0f}};
+
+  return points;
+}
+
+// The KdTree takes the input by value. In this example, creating a KdTree
+// results in a copy of the input point set.
+void BuildKdTreeWithCopy() {
+  int max_leaf_size = 12;
+  auto points = MakePointSet();
+
+  pico_tree::KdTree<std::vector<std::array<float, 3>>> tree(
+      points, max_leaf_size);
+
+  QueryTree(tree);
+}
+
+// The KdTree takes the input by value. In this example, the point sets are not
+// copied but moved into the KdTree. This prevents a copy.
+void BuildKdTreeWithMove() {
+  int max_leaf_size = 12;
+  auto points = MakePointSet();
+
+  pico_tree::KdTree<std::vector<std::array<float, 3>>> tree1(
+      std::move(points), max_leaf_size);
+
+  pico_tree::KdTree<std::vector<std::array<float, 3>>> tree2(
+      MakePointSet(), max_leaf_size);
+
+  QueryTree(tree1);
+  QueryTree(tree2);
+}
+
+// The KdTree takes the input by value. In this example, the input is taken by
+// reference. This prevents a copy.
+void BuildKdTreeWithReference() {
+  int max_leaf_size = 12;
+  auto points = MakePointSet();
+
+  // By reference.
+  pico_tree::KdTree<std::reference_wrapper<std::vector<std::array<float, 3>>>>
+      tree1(points, max_leaf_size);
+
+  // By const reference.
+  pico_tree::KdTree<
+      std::reference_wrapper<std::vector<std::array<float, 3>> const>>
+      tree2(points, max_leaf_size);
+
+  QueryTree(tree1);
+  QueryTree(tree2);
+}
+
+int main() {
+  BuildKdTreeWithReference();
+  BuildKdTreeWithMove();
+  BuildKdTreeWithCopy();
+  return 0;
+}