def get_weighted_edges(
faces: np.ndarray,
self_edges: bool = True) -> Tuple[np.ndarray, np.ndarray]:
r"""Gets unique edges and degree weights from a triangular mesh.
The shorthands used below are:
`T`: The number of triangles in the mesh.
`E`: The number of unique directed edges in the mesh.
Args:
faces: A [T, 3] `int32` numpy.ndarray of triangle vertex indices.
self_edges: A `bool` flag. If true, then for every vertex 'i' an edge
[i, i] is added to edge list.
Returns:
edges: A [E, 2] `int32` numpy.ndarray of directed edges.
weights: A [E] `float32` numpy.ndarray denoting edge weights.
The degree of a vertex is the number of edges incident on the vertex,
including any self-edges. The weight for an edge $w_{ij}$ connecting vertex
$v_i$ and vertex $v_j$ is defined as,
$$
w_{ij} = 1.0 / degree(v_i)
\sum_{j} w_{ij} = 1
$$
"""
edges = mesh_utils.extract_unique_edges_from_triangular_mesh(
faces, directed_edges=True).astype(np.int32)
if self_edges:
vertices = np.expand_dims(np.unique(edges[:, 0]), axis=1)
self_edges = np.concatenate((vertices, vertices), axis=1)
edges = np.unique(np.concatenate((edges, self_edges), axis=0), axis=0)
weights = mesh_utils.get_degree_based_edge_weights(edges, dtype=np.float32)
return edges, weights
def _weighted_edges(triangles):
"""Gets unique edges and degree weights from a triangular mesh."""
edges = mesh_utils.extract_unique_edges_from_triangular_mesh(
triangles, directed_edges=True).astype(np.int32)
weights = mesh_utils.get_degree_based_edge_weights(edges,
dtype=np.float32)
return edges, weights
def test_get_degree_based_edge_weights_preset(self, test_inputs,
test_dtype, test_outputs):
"""Tests that the output contain the expected edges."""
weights = utils.get_degree_based_edge_weights(test_inputs, test_dtype)
self.assertAllClose(weights.tolist(), test_outputs)
def test_get_degree_based_edge_weights_invalid_edges_raised(
self, invalid_input, error_msg):
"""Tests that the shape exceptions are properly raised."""
with self.assertRaisesRegexp(ValueError, error_msg):
utils.get_degree_based_edge_weights(invalid_input)
def test_get_degree_based_edge_weights_dtype_raised(
self, invalid_type, error_msg):
"""Tests that the shape exceptions are properly raised."""
with self.assertRaisesRegexp(ValueError, error_msg):
utils.get_degree_based_edge_weights(np.array(((1, 1), )),
invalid_type)
