Graph Factories¶
Creating graphs can be accomplished using factory methods. During runtime the
type of the graph can be queried using Graph.type
which returns a
GraphType
instance. This allows algorithms to adjust their
behavior depending on the graph they are working on.
Graph¶
The main factory function which creates graphs is jgrapht.create_graph()
.
Depending on the given parameters different types of graphs can be represented. All graphs
returned by this function are instances of jgrapht.types.Graph
.
Most users should create graphs using this function:

jgrapht.
create_graph
(directed=True, allowing_self_loops=False, allowing_multiple_edges=False, weighted=True, dag=False, any_hashable=False, vertex_supplier=None, edge_supplier=None)[source]¶ Create a graph.
By default this function creates graphs with integer vertices. When parameter any_hashable is true, the returned graph will be able to (a) have any hashable as vertices and edges, and (b) associate attributes/properties with the vertices and edges. Such a anyhashable graph needs to be able to create new objects for vertices and edges. This is accomplished by providing two functions called vertex supplier and edge supplier. If not provided by the user, the default implementation creates instances of
object
. Parameters
directed – if True the graph will be directed, otherwise undirected
allowing_self_loops – if True the graph will allow the addition of selfloops
allowing_multiple_edges – if True the graph will allow multipleedges
weighted – if True the graph will be weighted, otherwise unweighted
dag – if True the graph will be a DAG (directed acyclic graph). An error will be raised if either directed is False or allowing_self_loops is True. The returned graph will be an instance of
DirectedAcyclicGraph
any_hashable – if True then the graph will allow the use of any hashable as vertices and edges instead of just integers. This also makes the graph an instance of
AttributesGraph
vertex_supplier – used only in the case that the graph allows any hashable as vertices/edges. Called everytime the graph needs to create a new vertex. If not given, then object instances are used.
edge_supplier – used only in the case that the graph allows any hashable as vertices/edges. Called everytime the graph needs to create a new edge. If not given, then object instances are used.
 Returns
a graph
 Return type
Sparse Graph¶
The following function creates a special sparse graph representation which has certain benefits and certain drawbacks. The benefits are that (a) it is much smaller w.r.t memory consumption and (b) it is also usually much faster. The drawbacks are that the sparse representation (a) cannot be modified after construction and (b) is forces a user to use vertex and edges that are integers starting from 0 in a continuous range. Since modification is not possible, a user needs to bulkload the graph by providing both the number of vertices and all edges before hand.

jgrapht.
create_sparse_graph
(edgelist, num_of_vertices=None, directed=True, weighted=True, any_hashable=False, vertex_supplier=None, edge_supplier=None)[source]¶ Create a sparse graph.
By default this function creates graphs with integer vertices. When parameter any_hashable is true, the returned graph will be able to (a) have any hashable as vertices and edges, and (b) associate attributes/properties with the vertices and edges. Such a anyhashable graph needs to be able to create new objects for vertices and edges. This is accomplished by providing two functions called vertex supplier and edge supplier. If not provided by the user, the default implementation creates instances of
object
.The structure (topology) of a sparse graph is unmodifiable, but weights and properties can be modified.
 Parameters
edgelist – list of tuple (u,v) or (u,v,weight) for weighted graphs. If any_hashable is false, the vertices must be integers.
num_of_vertices – number of vertices in the graph. Vertices always start from 0 and increase continuously. If not explicitly given and any_hashable is false, the edgelist will be traversed in order to find out the number of vertices
directed – if True the graph will be directed, otherwise undirected
weighted – if True the graph will be weighted, otherwise unweighted
any_hashable – if True then the graph will allow the use of any hashable as vertices and edges instead of just integers. This also makes the graph an instance of
AttributesGraph
vertex_supplier – used only in the case that the graph allows any hashable as vertices/edges. Called everytime the graph needs to create a new vertex. If not given, then object instances are used.
edge_supplier – used only in the case that the graph allows any hashable as vertices/edges. Called everytime the graph needs to create a new edge. If not given, then object instances are used.
 Returns
a graph
 Return type
A helper function jgrapht.copy_to_sparse_graph()
can help in order to create a sparse
graph from another graph.

jgrapht.
copy_to_sparse_graph
(graph)[source]¶ Copy a graph to a sparse graph.
Note
Sparse graphs are unmodifiable w.r.t their structure (topology). Attempting to alter one will result in an error being raised. Attributes and edge weights can be modified.
 Parameters
graph – the input graph
 Returns
a sparse graph
 Return type
Building sparse graphs can be performed by using edge lists. See the section edge list importers.