add Mesh.to_lines() function

Author: ricardoavelino

src/compas/datastructures/mesh/mesh.py

@@ -377,15 +377,15 @@ def from_lines(cls, lines, delete_boundary_face=False, precision=None):
         return mesh
 
     def to_lines(self):
-        """Convert the mesh to a collection of lines.
+        """Return the lines of the mesh as pairs of start and end point coordinates.
 
         Returns
         -------
         list[tuple[list[float], list[float]]]
-            A list of lines each defined by a pair of points.
+            A list of lines each defined by a pair of point coordinates.
 
         """
-        raise NotImplementedError
+        return [self.edge_coordinates(u, v) for u, v in self.edges()]
 
     @classmethod
     def from_polylines(cls, boundary_polylines, other_polylines):

src/compas/datastructures/network/network.py

@@ -221,6 +221,7 @@ def from_pointcloud(cls, cloud, degree=3):
         Returns
         -------
         :class:`~compas.datastructures.Network`
+            A network object.
 
         """
         network = cls()
@@ -256,6 +257,7 @@ def to_points(self):
         Returns
         -------
         list[list[float]]
+            A list with the coordinates of the vertices of the network.
 
         """
         return [self.node_coordinates(key) for key in self.nodes()]
@@ -266,6 +268,7 @@ def to_lines(self):
         Returns
         -------
         list[tuple[list[float], list[float]]]
+            A list of lines each defined by a pair of point coordinates.
 
         """
         return [self.edge_coordinates(u, v) for u, v in self.edges()]

tests/compas/datastructures/test_mesh.py

@@ -203,6 +203,14 @@ def test_to_vertices_and_faces_triangulated():
     assert len(vertices) == 32
     assert len(faces) == 60
 
+
+def test_to_lines():
+    lines = compas.json_load(compas.get('lines.json'))
+    mesh = Mesh.from_lines(lines)
+    lines = mesh.to_lines()
+    assert len(lines) == mesh.number_of_edges()
+
+
 # --------------------------------------------------------------------------
 # helpers
 # --------------------------------------------------------------------------