disconnected mesh and network elements based on compas.topology.connected_components

mesh and network explode

Author: Robin Oval

src/compas/datastructures/mesh/__init__.py

@@ -16,6 +16,7 @@
 from .bbox import *
 from .descent import *
 from .duality import *
+from .explode import *
 from .geodesics import *
 from .join import *
 from .laplacian import *

src/compas/datastructures/mesh/explode.py

@@ -0,0 +1,114 @@
+from __future__ import print_function
+from __future__ import absolute_import
+from __future__ import division
+
+from compas.topology import connected_components
+
+__all__ = [
+    'mesh_disconnected_vertices',
+    'mesh_disconnected_faces',
+    'mesh_explode',
+]
+
+def mesh_disconnected_vertices(mesh):
+    """Get the disconnected vertex groups in a mesh.
+
+    Parameters
+    ----------
+    mesh : Mesh
+        A mesh.
+
+    Returns
+    -------
+    parts : list
+        The list of disconnected vertex groups.
+
+    """
+
+    return connected_components(mesh.adjacency)
+
+def mesh_disconnected_faces(mesh):
+    """Get the disconnected face groups in a mesh.
+
+    Parameters
+    ----------
+    mesh : Mesh
+        A mesh.
+
+    Returns
+    -------
+    parts : list
+        The list of disconnected face groups.
+
+    """
+
+    parts = mesh_disconnected_vertices(mesh)
+
+    return [set([fkey for vkey in part for fkey in mesh.vertex_faces(vkey)]) for part in parts]
+
+def mesh_explode(mesh, cls=None):
+    """Explode a mesh into its disconnected parts.
+
+    Parameters
+    ----------
+    mesh : Mesh
+        A mesh.
+
+    Returns
+    -------
+    exploded_meshes : list
+        The list of the meshes from the exploded mesh parts.
+
+    """
+
+    if cls is None:
+        cls = type(mesh)
+
+    parts = mesh_disconnected_faces(mesh)
+
+    exploded_meshes = []
+
+    for part in parts:
+        
+        vertex_keys = list(set([vkey for fkey in part for vkey in mesh.face_vertices(fkey)]))
+        vertices = [mesh.vertex_coordinates(vkey) for vkey in vertex_keys]
+        
+        key_to_index = {vkey: i for i, vkey in enumerate(vertex_keys)}
+        faces = [ [key_to_index[vkey] for vkey in mesh.face_vertices(fkey)] for fkey in part]
+        
+        exploded_meshes.append(cls.from_vertices_and_faces(vertices, faces))
+
+    return exploded_meshes
+
+# ==============================================================================
+# Main
+# ==============================================================================
+
+if __name__ == '__main__':
+
+    from compas.datastructures import Mesh
+
+    vertices = [
+        [0.0, 0.0, 0.0],
+        [1.0, 0.0, 0.0],
+        [2.0, 0.0, 0.0],
+        [2.0, 0.0, 0.0],
+        [3.0, 0.0, 0.0],
+        [0.0, 1.0, 0.0],
+        [1.0, 1.0, 0.0],
+        [2.0, 1.0, 0.0],
+        [2.0, 1.0, 0.0],
+        [3.0, 1.0, 0.0],
+    ]
+
+    faces = [
+        [0, 1, 6, 5],
+        [1, 2, 7, 6],
+        [3, 4, 9, 8]
+        ]
+
+    mesh = Mesh.from_vertices_and_faces(vertices, faces)
+
+    print(mesh_disconnected_vertices(mesh))
+    print(mesh_disconnected_faces(mesh))
+    print(mesh_explode(mesh))

src/compas/datastructures/network/__init__.py

@@ -8,10 +8,10 @@
 from .combinatorics import *
 from .complementarity import *
 from .duality import *
+from .explode import *
 from .parallelisation import *
 from ._planarity import *
 from .smoothing import *
 from .transformations import *
 
-
 __all__ = [name for name in dir() if not name.startswith('_')]

src/compas/datastructures/network/explode.py

@@ -0,0 +1,113 @@
+from __future__ import print_function
+from __future__ import absolute_import
+from __future__ import division
+
+from compas.topology import connected_components
+
+__all__ = [
+    'network_disconnected_vertices',
+    'network_disconnected_edges',
+    'network_explode'
+]
+
+def network_disconnected_vertices(network):
+    """Get the disconnected vertex groups in a network.
+
+    Parameters
+    ----------
+    network : Network
+        A network.
+
+    Returns
+    -------
+    list
+        The list of disconnected vertex groups.
+
+    """
+
+    return connected_components(network.adjacency)
+
+def network_disconnected_edges(network):
+    """Get the disconnected edge groups in a network.
+
+    Parameters
+    ----------
+    network : Network
+        A network.
+
+    Returns
+    -------
+    parts : list
+        The list of disconnected edge groups.
+
+    """
+
+
+    parts = network_disconnected_vertices(network)
+
+    return [[(u, v) for u in part for v in network.vertex_neighbors(u) if u < v] for part in parts]
+
+
+def network_explode(network, cls=None):
+    """Explode a network into its disconnected parts.
+
+    Parameters
+    ----------
+    network : Network
+        A network.
+
+    Returns
+    -------
+    exploded_networks : list
+        The list of the networks from the exploded network parts.
+
+    """
+
+    if cls is None:
+        cls = type(network)
+
+    parts = network_disconnected_edges(network)
+
+    exploded_networks = []
+
+    for part in parts:
+        
+        vertex_keys = list(set([vkey for edge in part for vkey in edge]))
+        vertices = [network.vertex_coordinates(vkey) for vkey in vertex_keys]
+        
+        key_to_index = {vkey: i for i, vkey in enumerate(vertex_keys)}
+        edges = [ (key_to_index[u], key_to_index[v]) for u, v in part]
+        
+        exploded_networks.append(cls.from_vertices_and_edges(vertices, edges))
+
+    return exploded_networks
+
+
+
+# ==============================================================================
+# Main
+# ==============================================================================
+
+if __name__ == "__main__":
+    
+    from compas.datastructures import Network
+
+    vertices = [
+        [0.0, 0.0, 0.0],
+        [1.0, 0.0, 0.0],
+        [2.0, 0.0, 0.0],
+        [3.0, 0.0, 0.0],
+        [4.0, 0.0, 0.0],
+    ]
+
+    edges = [
+        (0, 1),
+        (2, 3),
+        (3, 4),
+    ]
+
+    network = Network.from_vertices_and_edges(vertices, edges)
+
+    print(network_disconnected_vertices(network))
+    print(network_disconnected_edges(network))
+    print(network_explode(network))