use eigen for native numpy output

CMakeLists.txt

@@ -17,6 +17,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 find_package(Python REQUIRED COMPONENTS Interpreter Development.Module)
 find_package(pybind11 CONFIG REQUIRED)
 find_package(CGAL REQUIRED COMPONENTS ImageIO)
+find_package(Eigen3 3.3 REQUIRED NO_MODULE)
 
 # make cache variables for install destinations
 include(GNUInstallDirs)

cpp/CMakeLists.txt

@@ -12,5 +12,6 @@ add_library(${PROJECT_NAME} SHARED
     ${${PROJECT_NAME}_HEADERS}
     ${${PROJECT_NAME}_SOURCES}
 )
+target_link_libraries(${PROJECT_NAME} PUBLIC Eigen3::Eigen)
 
 install(TARGETS ${PROJECT_NAME} DESTINATION "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
\ No newline at end of file

cpp/LabelledTetrahedralMesh.cpp

 #include "LabelledTetrahedralMesh.h"
 
 
-std::vector< std::vector<double> > LabelledTetrahedralMesh::vertexPoints(void) const
+Eigen::ArrayX3d LabelledTetrahedralMesh::vertexPoints(void) const
 {
-    return this->_vertex_points;
+    Eigen::ArrayX3d vertex_points(this->_vertex_points.size(), 3);
+    for (int i=0; i<this->_vertex_points.size(); i++) {
+        for (int dim=0; dim<3; dim++) {
+            vertex_points(i, dim) = this->_vertex_points[i][dim];
+        }
+    }
+    return vertex_points;
 }
 
-void LabelledTetrahedralMesh::addPoint(const std::vector<double>& point)
+void LabelledTetrahedralMesh::addPoint(Eigen::Array3d point)
 {
-    this->_vertex_points.push_back(point);
+    std::vector<double> _point = std::vector<double> {point(0, 0), point(0, 1), point(0, 2)};
+    this->_vertex_points.push_back(_point);
 }

cpp/LabelledTetrahedralMesh.h

 #pragma once
 
 #include <vector>
+#include <Eigen/Dense>
 
 class LabelledTetrahedralMesh
 {
@@ -9,8 +10,8 @@ public:
     ~LabelledTetrahedralMesh(void) = default;
 
 public:
-    std::vector< std::vector<double> > vertexPoints(void) const;
-    void addPoint(const std::vector<double>& point);
+    Eigen::ArrayX3d vertexPoints(void) const;
+    void addPoint(Eigen::Array3d point);
 
 private:
     std::vector< std::vector<double> > _vertex_points;

tests/test_tetrahedral_mesh.py

@@ -13,4 +13,4 @@ class TestTetrahedralMesh(unittest.TestCase):
         mesh = LabelledTetrahedralMesh()
         mesh.add_point([0, 0, 0])
         points = mesh.vertex_points()
-        assert len(points) == 1
+        assert points.shape == (1, 3)

wrp/LabelledTetrahedralMeshWrapper.cpp

 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h> // This header is needed to work with STL containers like std::vector
+#include <pybind11/eigen.h>
 
 #include "LabelledTetrahedralMesh.h"