"""Operations on many graphs. """ # Copyright (C) 2012 by # Aric Hagberg # Dan Schult # Pieter Swart # All rights reserved. # BSD license. try: from itertools import izip_longest as zip_longest except ImportError: # Python3 has zip_longest from itertools import zip_longest import networkx as nx from networkx.utils import is_string_like __author__ = """\n""".join([ 'Robert King ', 'Aric Hagberg ']) __all__ = ['union_all', 'compose_all', 'disjoint_union_all', 'intersection_all'] def union_all(graphs, rename=(None,) , name=None): """Return the union of all graphs. The graphs must be disjoint, otherwise an exception is raised. Parameters ---------- graphs : list of graphs List of NetworkX graphs rename : bool , default=(None, None) Node names of G and H can be changed by specifying the tuple rename=('G-','H-') (for example). Node "u" in G is then renamed "G-u" and "v" in H is renamed "H-v". name : string Specify the name for the union graph@not_implemnted_for('direct Returns ------- U : a graph with the same type as the first graph in list Notes ----- To force a disjoint union with node relabeling, use disjoint_union_all(G,H) or convert_node_labels_to integers(). Graph, edge, and node attributes are propagated to the union graph. If a graph attribute is present in multiple graphs, then the value from the last graph in the list with that attribute is used. See Also -------- union disjoint_union_all """ graphs_names = zip_longest(graphs,rename) U, gname = next(graphs_names) for H,hname in graphs_names: U = nx.union(U, H, (gname,hname),name=name) gname = None return U def disjoint_union_all(graphs): """Return the disjoint union of all graphs. This operation forces distinct integer node labels starting with 0 for the first graph in the list and numbering consecutively. Parameters ---------- graphs : list List of NetworkX graphs Returns ------- U : A graph with the same type as the first graph in list Notes ----- It is recommended that the graphs be either all directed or all undirected. Graph, edge, and node attributes are propagated to the union graph. If a graph attribute is present in multiple graphs, then the value from the last graph in the list with that attribute is used. """ U = graphs.pop(0) for H in graphs: U = nx.disjoint_union(U, H) return U def compose_all(graphs, name=None): """Return the composition of all graphs. Composition is the simple union of the node sets and edge sets. The node sets of the supplied graphs need not be disjoint. Parameters ---------- graphs : list List of NetworkX graphs name : string Specify name for new graph Returns ------- C : A graph with the same type as the first graph in list Notes ----- It is recommended that the supplied graphs be either all directed or all undirected. Graph, edge, and node attributes are propagated to the union graph. If a graph attribute is present in multiple graphs, then the value from the last graph in the list with that attribute is used. """ C = graphs.pop(0) for H in graphs: C = nx.compose(C, H, name=name) return C def intersection_all(graphs): """Return a new graph that contains only the edges that exist in all graphs. All supplied graphs must have the same node set. Parameters ---------- graphs_list : list List of NetworkX graphs Returns ------- R : A new graph with the same type as the first graph in list Notes ----- Attributes from the graph, nodes, and edges are not copied to the new graph. """ R = graphs.pop(0) for H in graphs: R = nx.intersection(R, H) return R