ENH: Adding Python example to create mesh and cells

Author: PranjalSahu

src/Core/Mesh/AddPointsAndEdges/Code.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python
+
+# Copyright NumFOCUS
+#
+# 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.txt
+#
+# 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.
+
+
+import itk
+import numpy as np
+
+Dimension = 3
+MeshType = itk.Mesh[itk.F, Dimension]
+
+
+def CreatePointOnlyMesh():
+    mesh = MeshType.New()
+
+    # Create points
+    p0 = [-1.0, -1.0, 0.0]  # first  point ( -1, -1, 0 )
+    p1 = [1.0, -1.0, 0.0]  # second point (  1, -1, 0 )
+    p2 = [1.0, 1.0, 0.0]  # third  point (  1,  1, 0 )
+    p3 = [1.0, 1.0, 1.0]  # fourth  point (  1,  1, 1 )
+
+    mesh.SetPoint(0, p0)
+    mesh.SetPoint(1, p1)
+    mesh.SetPoint(2, p2)
+    mesh.SetPoint(3, p3)
+
+    print("Points = ", mesh.GetNumberOfPoints())
+
+    # Access points
+    points = mesh.GetPoints()
+    for i in range(points.Size()):
+        p = mesh.GetPoint(i)
+        print(p)
+
+    return mesh
+
+
+def CreateMeshWithEdges():
+    mesh = CreatePointOnlyMesh()
+
+    # Point Ids for the two cells
+    pointId0 = 0
+    pointId1 = 1
+
+    pointId2 = 1
+    pointId3 = 2
+
+    # Create cells array and insert points in them
+    # Each cell is of line type here
+    cells_array = np.zeros(4, dtype=np.uint64)
+    cells_array[0] = pointId0
+    cells_array[1] = pointId1
+
+    cells_array[2] = pointId2
+    cells_array[3] = pointId3
+
+    cells_vector = itk.vector_container_from_array(cells_array.flatten())
+
+    # When all cells are same use the second arguement to pass the cell type
+    mesh.SetCellsArray(cells_vector, itk.CommonEnums.CellGeometry_LINE_CELL)
+
+    number_of_cells = mesh.GetNumberOfCells()
+    all_cells = mesh.GetCells()
+
+    # Iterate over the cells and print the points present in them
+    for i in range(number_of_cells):
+        current_cell = all_cells.GetElement(i)
+        point_ids = current_cell.GetPointIdsContainer()
+        print(point_ids)
+
+
+CreateMeshWithEdges()