General Graph Functions

This module provides some general graph functionality.

pyrigi.graph._general.adjacency_matrix(graph, vertex_order=None)[source]

Return the adjacency matrix of the graph.

Parameters:

  • graph (Graph)

  • vertex_order (Sequence[Vertex]) – By listing vertices in the preferred order, the adjacency matrix can be computed in a way the user expects. If no vertex order is provided, vertex_list() is used.

Return type:

MutableDenseMatrix

Examples

>>> G = Graph([(0,1), (1,2), (1,3)])
>>> adjacency_matrix(G)
Matrix([
[0, 1, 0, 0],
[1, 0, 1, 1],
[0, 1, 0, 0],
[0, 1, 0, 0]])

Notes

networkx.linalg.graphmatrix.adjacency_matrix() requires scipy. To avoid unnecessary imports, the function is implemented here.

pyrigi.graph._general.degree_sequence(graph, vertex_order=None)[source]

Return a list of degrees of the vertices of the graph.

Parameters:

  • graph (Graph)

  • vertex_order (Sequence[Vertex]) – By listing vertices in the preferred order, the degree_sequence can be computed in a way the user expects. If no vertex order is provided, vertex_list() is used.

Return type:

list[int]

Examples

>>> G = Graph([(0,1), (1,2)])
>>> degree_sequence(G)
[1, 2, 1]
pyrigi.graph._general.edge_list(graph, as_tuples=False)[source]

Return the list of edges.

The output is sorted if possible, otherwise, the internal order is used instead.

Parameters:

  • graph (Graph)

  • as_tuples (bool) – If True, all edges are returned as tuples instead of lists.

Return type:

list[Edge]

Examples

>>> G = Graph([[0, 3], [3, 1], [0, 1], [2, 0]])
>>> edge_list(G)
[[0, 1], [0, 2], [0, 3], [1, 3]]

>>> G = Graph.from_vertices(['a', 'c', 'b'])
>>> edge_list(G)
[]

>>> G = Graph([['c', 'b'], ['b', 'a']])
>>> edge_list(G)
[['a', 'b'], ['b', 'c']]

>>> G = Graph([['c', 1], [2, 'a']]) # incomparable vertices
>>> edge_list(G)
[('c', 1), (2, 'a')]
pyrigi.graph._general.max_degree(graph)[source]

Return the maximum of the vertex degrees.

Return type:

int

Parameters:

graph (Graph)

Examples

>>> G = Graph([(0,1), (1,2)])
>>> max_degree(G)
2
pyrigi.graph._general.min_degree(graph)[source]

Return the minimum of the vertex degrees.

Return type:

int

Parameters:

graph (Graph)

Examples

>>> G = Graph([(0,1), (1,2)])
>>> min_degree(G)
1
pyrigi.graph._general.vertex_list(graph)[source]

Return the list of vertices.

The output is sorted if possible, otherwise, the internal order is used instead.

Return type:

list[Vertex]

Parameters:

graph (Graph)

Examples

>>> G = Graph.from_vertices_and_edges([2, 0, 3, 1], [[0, 1], [0, 2], [0, 3]])
>>> vertex_list(G)
[0, 1, 2, 3]

>>> G = Graph.from_vertices(['c', 'a', 'b'])
>>> vertex_list(G)
['a', 'b', 'c']

>>> G = Graph.from_vertices(['b', 1, 'a']) # incomparable vertices
>>> vertex_list(G)
['b', 1, 'a']