Export ngcore Arrays

libsrc/core/python_ngcore.hpp

@@ -26,7 +26,48 @@ namespace ngcore
       throw py::type_error("Cannot convert Python object to C Array");
     return arr;
   }
-  
+
+  template <typename T, typename TIND=typename FlatArray<T>::index_type>
+  void ExportArray (py::module &m)
+  {
+      using TFlat = FlatArray<T, TIND>;
+      using TArray = Array<T, TIND>;
+      std::string suffix = std::string(typeid(T).name()) + "_" + typeid(TIND).name();
+      std::string fname = std::string("FlatArray_") + suffix;
+      py::class_<TFlat>(m, fname.c_str())
+        .def ("__len__", [] ( TFlat &self ) { return self.Size(); } )
+        .def ("__getitem__",
+              [](TFlat & self, TIND i) -> T&
+                             {
+                               static constexpr int base = IndexBASE<TIND>();
+                               static_assert(base==0 || base==1, "IndexBASE not in [0,1]");
+                               if (i < 0 || i >= self.Size())
+                                 throw py::index_error();
+                               if(base==1) i++;
+                               return self[i]; // Access from Python is always 0-based
+                             },
+              py::return_value_policy::reference)
+        .def("__iter__", [] ( TFlat & self) {
+             return py::make_iterator (self.begin(),self.end());
+             }, py::keep_alive<0,1>()) // keep array alive while iterator is used
+
+      ;
+
+      std::string aname = std::string("Array_") + suffix;
+      py::class_<TArray, TFlat>(m, aname.c_str())
+        .def(py::init([] (size_t n) { return new TArray(n); }),py::arg("n"), "Makes array of given length")
+        .def(py::init([] (std::vector<T> const & x)
+                  {
+                    size_t s = x.size();
+                    TArray tmp(s);
+                    for (size_t i : Range(tmp))
+                      tmp[TIND(i)] = x[i];
+                    return tmp;
+                  }), py::arg("vec"), "Makes array with given list of elements")
+
+      ;
+    }
+
   void NGCORE_API SetFlag(Flags &flags, std::string s, py::object value);
   // Parse python kwargs to flags
   Flags NGCORE_API CreateFlagsFromKwArgs(const py::kwargs& kwargs, py::object pyclass = py::none(),

libsrc/core/python_ngcore_export.cpp

@@ -6,6 +6,11 @@ using namespace std;
 
 PYBIND11_MODULE(pyngcore, m) // NOLINT
 {
+  ExportArray<int>(m);
+  ExportArray<unsigned>(m);
+  ExportArray<size_t>(m);
+  ExportArray<double>(m);
+
   py::class_<Flags>(m, "Flags")
     .def(py::init<>())
     .def("__str__", &ToString<Flags>)

libsrc/meshing/python_mesh.cpp

@@ -40,28 +40,6 @@ namespace netgen
 }
 
 
-template <typename T, int BASE = 0, typename TIND = int>
-void ExportArray (py::module &m)
-{
-  using TA = NgArray<T,BASE,TIND>;
-  string name = string("Array_") + typeid(T).name();
-  py::class_<NgArray<T,BASE,TIND>>(m, name.c_str())
-    .def ("__len__", [] ( NgArray<T,BASE,TIND> &self ) { return self.Size(); } )
-    .def ("__getitem__", 
-          FunctionPointer ([](NgArray<T,BASE,TIND> & self, TIND i) -> T&
-                           {
-                             if (i < BASE || i >= BASE+self.Size())
-                               throw py::index_error();
-                             return self[i];
-                           }),
-          py::return_value_policy::reference)
-    .def("__iter__", [] ( TA & self) {
-	return py::make_iterator (self.begin(),self.end());
-      }, py::keep_alive<0,1>()) // keep array alive while iterator is used
-
-    ;
-}
-
 void TranslateException (const NgException & ex)
 {
   string err = string("Netgen exception: ")+ex.What();
@@ -527,11 +505,11 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
 
   
 
-  ExportArray<Element,0,size_t>(m);
+  ExportArray<Element,size_t>(m);
-  ExportArray<Element2d,0,size_t>(m);
+  ExportArray<Element2d,size_t>(m);
-  ExportArray<Segment,0,size_t>(m);
+  ExportArray<Segment,size_t>(m);
   ExportArray<Element0d>(m);
-  ExportArray<MeshPoint,PointIndex::BASE,PointIndex>(m);
+  ExportArray<MeshPoint,PointIndex>(m);
   ExportArray<FaceDescriptor>(m);
 
   py::implicitly_convertible< int, PointIndex>();

tests/pytest/meshes.py

@@ -0,0 +1,11 @@
+import pytest
+
+@pytest.fixture
+def unit_mesh_2d():
+    import netgen.geom2d as g2d
+    return g2d.unit_square.GenerateMesh(maxh=0.2)
+
+@pytest.fixture
+def unit_mesh_3d():
+    import netgen.csg as csg
+    return csg.unit_cube.GenerateMesh(maxh=0.2)

tests/pytest/test_meshclass.py

@@ -0,0 +1,22 @@
+import pyngcore
+import netgen
+
+from meshes import unit_mesh_3d
+
+def test_element_arrays(unit_mesh_3d):
+    mesh = unit_mesh_3d
+    el0 = mesh.Elements0D()
+    el1 = mesh.Elements1D()
+    el2 = mesh.Elements2D()
+    el3 = mesh.Elements3D()
+    p = mesh.Points()
+
+    assert len(el2) > 0
+    assert len(el3) > 0
+    assert len(p) > 0
+
+    for el in el2:
+        assert len(el.vertices) == 3
+
+    for el in el3:
+        assert len(el.vertices) == 4