Graph

class compas.datastructures.Graph

Bases: Datastructure

Data structure for describing the relationships between nodes connected by edges.

Parameters:

default_node_attributesdict, optional

Default values for node attributes.

default_edge_attributesdict, optional

Default values for edge attributes.

namestr, optional

The name of the graph.

**kwargsdict, optional

Additional keyword arguments, which are stored in the attributes dict.

Attributes:

default_node_attributesdict[str, Any]

dictionary containing default values for the attributes of nodes. It is recommended to add a default to this dictionary using update_default_node_attributes() for every node attribute used in the data structure.

default_edge_attributesdict[str, Any]

dictionary containing default values for the attributes of edges. It is recommended to add a default to this dictionary using update_default_edge_attributes() for every edge attribute used in the data structure.

Methods

Constructors

from_edges	Create a new graph instance from information about the edges.
from_json	Construct an object of this type from a JSON file.
from_lines	Construct a graph from a set of lines represented by their start and end point coordinates.
from_networkx	Create a new graph instance from a NetworkX DiGraph instance.
from_nodes_and_edges	Construct a graph from nodes and edges.
from_obj	Construct a graph from the data contained in an OBJ file.
from_pointcloud	Construct a graph from random connections between the points of a pointcloud.

Conversions

to_json	Convert an object to its native data representation and save it to a JSON file.
to_lines	Return the lines of the graph as pairs of start and end point coordinates.
to_networkx	Create a new NetworkX graph instance from a graph.
to_obj	Write the graph to an OBJ file.
to_points	Return the coordinates of the graph.

Builders and Modifiers

add_edge	Add an edge and specify its attributes.
add_node	Add a node and specify its attributes (optional).
delete_edge	Delete an edge from the graph.
delete_node	Delete a node from the graph.
join_edges	Join the edges incidental on the given node, if there are exactly two incident edges.
split_edge	Split and edge by inserting a node along its length.

Accessors

edge_sample	Get the identifiers of a set of random edges.
edges	Iterate over the edges of the graph.
edges_where	Get edges for which a certain condition or set of conditions is true.
edges_where_predicate	Get edges for which a certain condition or set of conditions is true using a lambda function.
node_sample	Get a list of identifiers of a random set of n nodes.
nodes	Iterate over the nodes of the graph.
nodes_where	Get nodes for which a certain condition or set of conditions is true.
nodes_where_predicate	Get nodes for which a certain condition or set of conditions is true using a lambda function.

Attributes

edge_attribute	Get or set an attribute of an edge.
edge_attributes	Get or set multiple attributes of an edge.
edges_attribute	Get or set an attribute of multiple edges.
edges_attributes	Get or set multiple attributes of multiple edges.
node_attribute	Get or set an attribute of a node.
node_attributes	Get or set multiple attributes of a node.
nodes_attribute	Get or set an attribute of multiple nodes.
nodes_attributes	Get or set multiple attributes of multiple nodes.
update_default_edge_attributes	Update the default edge attributes.
update_default_node_attributes	Update the default node attributes.
unset_edge_attribute	Unset the attribute of an edge.
unset_node_attribute	Unset the attribute of a node.

Topology

complement	Generate the complement of a graph.
connected_nodes	Get groups of connected nodes.
connected_edges	Get groups of connected edges.
degree	Return the number of neighbors of a node.
degree_out	Return the number of outgoing neighbors of a node.
degree_in	Return the numer of incoming neighbors of a node.
exploded	Explode the graph into its connected components.
has_edge	Verify if the graph contains a specific edge.
has_node	Verify if a specific node is present in the graph.
is_leaf	Verify if a node is a leaf.
is_node_connected	Verify if a specific node is connected.
neighborhood	Return the nodes in the neighborhood of a node.
neighbors	Return the neighbors of a node.
neighbors_in	Return the incoming neighbors of a node.
neighbors_out	Return the outgoing neighbors of a node.
node_edges	Return the edges connected to a node.
number_of_edges	Compute the number of edges of the graph.
number_of_nodes	Compute the number of nodes of the graph.

Geometry

edge_coordinates	Return the coordinates of the start and end point of an edge.
edge_direction	Return the direction vector of an edge.
edge_end	Return the end point of an edge.
edge_length	Return the length of an edge.
edge_line	Return the line of an edge.
edge_midpoint	Return the location of the midpoint of an edge.
edge_point	Return the point at a parametric location along an edge.
edge_start	Return the start point of an edge.
edge_vector	Return the vector of an edge.
node_coordinates	Return the coordinates of a node.
node_point	Return the point of a node.
node_laplacian	Return the vector from the node to the centroid of its 1-ring neighborhood.
node_neighborhood_centroid	Return the computed centroid of the neighboring nodes.
transform	Transform all nodes of the graph.
transformed	Returns a transformed copy of this data structure.

Paths

shortest_path

Find the shortest path between two nodes using the A* algorithm.

Planarity

count_crossings	Count the number of crossings (pairs of crossing edges) in the graph.
embed_in_plane	Embed the graph in the plane.
find_crossings	Identify all pairs of crossing edges in a graph.
find_cycles	Find the faces of a graph.
is_crossed	Verify if a graph has crossing edges.
is_planar	Check if the graph is planar.
is_planar_embedding	Verify that a graph is embedded in the plane without crossing edges.
is_xy	Verify that a graph lies in the XY plane.

Matrices

adjacency_matrix	Creates a node adjacency matrix from a Graph datastructure.
connectivity_matrix	Creates a connectivity matrix from a Graph datastructure.
degree_matrix	Creates a degree matrix from a Graph datastructure.
laplacian_matrix	Creates a Laplacian matrix from a Graph datastructure.

Mappings

gkey_node	Returns a dictionary that maps geometric keys of a certain precision to the identifiers of the corresponding nodes.
node_gkey	Returns a dictionary that maps node identifiers to the corresponding geometric key up to a certain precision.
node_index	Returns a dictionary that maps node identifiers to their corresponding index in a node list or array.
edge_index	Returns a dictionary that maps edge identifiers (i.e.
index_node	Returns a dictionary that maps the indices of a node list to keys in a node dictionary.
index_edge	Returns a dictionary that maps edges in a list to the corresponding vertex identifier pairs.

Utilities

summary	Return a summary of the graph.
copy	Make an independent copy of the data object.
clear	Clear all the graph data.