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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/algorithms/operators/binary.py')
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diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/operators/binary.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/operators/binary.py new file mode 100644 index 00000000..08907bf6 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/operators/binary.py @@ -0,0 +1,450 @@ +""" +Operations on graphs including union, intersection, difference. +""" + +import networkx as nx + +__all__ = [ + "union", + "compose", + "disjoint_union", + "intersection", + "difference", + "symmetric_difference", + "full_join", +] +_G_H = {"G": 0, "H": 1} + + +@nx._dispatchable(graphs=_G_H, preserve_all_attrs=True, returns_graph=True) +def union(G, H, rename=()): + """Combine graphs G and H. The names of nodes must be unique. + + A name collision between the graphs will raise an exception. + + A renaming facility is provided to avoid name collisions. + + + Parameters + ---------- + G, H : graph + A NetworkX graph + + rename : iterable , optional + 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". + + Returns + ------- + U : A union graph with the same type as G. + + See Also + -------- + compose + :func:`~networkx.Graph.update` + disjoint_union + + Notes + ----- + To combine graphs that have common nodes, consider compose(G, H) + or the method, Graph.update(). + + disjoint_union() is similar to union() except that it avoids name clashes + by relabeling the nodes with sequential integers. + + Edge and node attributes are propagated from G and H to the union graph. + Graph attributes are also propagated, but if they are present in both G and H, + then the value from H is used. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2)]) + >>> H = nx.Graph([(0, 1), (0, 3), (1, 3), (1, 2)]) + >>> U = nx.union(G, H, rename=("G", "H")) + >>> U.nodes + NodeView(('G0', 'G1', 'G2', 'H0', 'H1', 'H3', 'H2')) + >>> U.edges + EdgeView([('G0', 'G1'), ('G0', 'G2'), ('G1', 'G2'), ('H0', 'H1'), ('H0', 'H3'), ('H1', 'H3'), ('H1', 'H2')]) + + + """ + return nx.union_all([G, H], rename) + + +@nx._dispatchable(graphs=_G_H, preserve_all_attrs=True, returns_graph=True) +def disjoint_union(G, H): + """Combine graphs G and H. The nodes are assumed to be unique (disjoint). + + This algorithm automatically relabels nodes to avoid name collisions. + + Parameters + ---------- + G,H : graph + A NetworkX graph + + Returns + ------- + U : A union graph with the same type as G. + + See Also + -------- + union + compose + :func:`~networkx.Graph.update` + + Notes + ----- + A new graph is created, of the same class as G. It is recommended + that G and H be either both directed or both undirected. + + The nodes of G are relabeled 0 to len(G)-1, and the nodes of H are + relabeled len(G) to len(G)+len(H)-1. + + Renumbering forces G and H to be disjoint, so no exception is ever raised for a name collision. + To preserve the check for common nodes, use union(). + + Edge and node attributes are propagated from G and H to the union graph. + Graph attributes are also propagated, but if they are present in both G and H, + then the value from H is used. + + To combine graphs that have common nodes, consider compose(G, H) + or the method, Graph.update(). + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2)]) + >>> H = nx.Graph([(0, 3), (1, 2), (2, 3)]) + >>> G.nodes[0]["key1"] = 5 + >>> H.nodes[0]["key2"] = 10 + >>> U = nx.disjoint_union(G, H) + >>> U.nodes(data=True) + NodeDataView({0: {'key1': 5}, 1: {}, 2: {}, 3: {'key2': 10}, 4: {}, 5: {}, 6: {}}) + >>> U.edges + EdgeView([(0, 1), (0, 2), (1, 2), (3, 4), (4, 6), (5, 6)]) + """ + return nx.disjoint_union_all([G, H]) + + +@nx._dispatchable(graphs=_G_H, returns_graph=True) +def intersection(G, H): + """Returns a new graph that contains only the nodes and the edges that exist in + both G and H. + + Parameters + ---------- + G,H : graph + A NetworkX graph. G and H can have different node sets but must be both graphs or both multigraphs. + + Raises + ------ + NetworkXError + If one is a MultiGraph and the other one is a graph. + + Returns + ------- + GH : A new graph with the same type as G. + + Notes + ----- + Attributes from the graph, nodes, and edges are not copied to the new + graph. If you want a new graph of the intersection of G and H + with the attributes (including edge data) from G use remove_nodes_from() + as follows + + >>> G = nx.path_graph(3) + >>> H = nx.path_graph(5) + >>> R = G.copy() + >>> R.remove_nodes_from(n for n in G if n not in H) + >>> R.remove_edges_from(e for e in G.edges if e not in H.edges) + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2)]) + >>> H = nx.Graph([(0, 3), (1, 2), (2, 3)]) + >>> R = nx.intersection(G, H) + >>> R.nodes + NodeView((0, 1, 2)) + >>> R.edges + EdgeView([(1, 2)]) + """ + return nx.intersection_all([G, H]) + + +@nx._dispatchable(graphs=_G_H, returns_graph=True) +def difference(G, H): + """Returns a new graph that contains the edges that exist in G but not in H. + + The node sets of H and G must be the same. + + Parameters + ---------- + G,H : graph + A NetworkX graph. G and H must have the same node sets. + + Returns + ------- + D : A new graph with the same type as G. + + Notes + ----- + Attributes from the graph, nodes, and edges are not copied to the new + graph. If you want a new graph of the difference of G and H with + the attributes (including edge data) from G use remove_nodes_from() + as follows: + + >>> G = nx.path_graph(3) + >>> H = nx.path_graph(5) + >>> R = G.copy() + >>> R.remove_nodes_from(n for n in G if n in H) + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2), (1, 3)]) + >>> H = nx.Graph([(0, 1), (1, 2), (0, 3)]) + >>> R = nx.difference(G, H) + >>> R.nodes + NodeView((0, 1, 2, 3)) + >>> R.edges + EdgeView([(0, 2), (1, 3)]) + """ + # create new graph + if not G.is_multigraph() == H.is_multigraph(): + raise nx.NetworkXError("G and H must both be graphs or multigraphs.") + R = nx.create_empty_copy(G, with_data=False) + + if set(G) != set(H): + raise nx.NetworkXError("Node sets of graphs not equal") + + if G.is_multigraph(): + edges = G.edges(keys=True) + else: + edges = G.edges() + for e in edges: + if not H.has_edge(*e): + R.add_edge(*e) + return R + + +@nx._dispatchable(graphs=_G_H, returns_graph=True) +def symmetric_difference(G, H): + """Returns new graph with edges that exist in either G or H but not both. + + The node sets of H and G must be the same. + + Parameters + ---------- + G,H : graph + A NetworkX graph. G and H must have the same node sets. + + Returns + ------- + D : A new graph with the same type as G. + + Notes + ----- + Attributes from the graph, nodes, and edges are not copied to the new + graph. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2), (1, 2), (1, 3)]) + >>> H = nx.Graph([(0, 1), (1, 2), (0, 3)]) + >>> R = nx.symmetric_difference(G, H) + >>> R.nodes + NodeView((0, 1, 2, 3)) + >>> R.edges + EdgeView([(0, 2), (0, 3), (1, 3)]) + """ + # create new graph + if not G.is_multigraph() == H.is_multigraph(): + raise nx.NetworkXError("G and H must both be graphs or multigraphs.") + R = nx.create_empty_copy(G, with_data=False) + + if set(G) != set(H): + raise nx.NetworkXError("Node sets of graphs not equal") + + gnodes = set(G) # set of nodes in G + hnodes = set(H) # set of nodes in H + nodes = gnodes.symmetric_difference(hnodes) + R.add_nodes_from(nodes) + + if G.is_multigraph(): + edges = G.edges(keys=True) + else: + edges = G.edges() + # we could copy the data here but then this function doesn't + # match intersection and difference + for e in edges: + if not H.has_edge(*e): + R.add_edge(*e) + + if H.is_multigraph(): + edges = H.edges(keys=True) + else: + edges = H.edges() + for e in edges: + if not G.has_edge(*e): + R.add_edge(*e) + return R + + +@nx._dispatchable(graphs=_G_H, preserve_all_attrs=True, returns_graph=True) +def compose(G, H): + """Compose graph G with H by combining nodes and edges into a single graph. + + The node sets and edges sets do not need to be disjoint. + + Composing preserves the attributes of nodes and edges. + Attribute values from H take precedent over attribute values from G. + + Parameters + ---------- + G, H : graph + A NetworkX graph + + Returns + ------- + C: A new graph with the same type as G + + See Also + -------- + :func:`~networkx.Graph.update` + union + disjoint_union + + Notes + ----- + It is recommended that G and H be either both directed or both undirected. + + For MultiGraphs, the edges are identified by incident nodes AND edge-key. + This can cause surprises (i.e., edge `(1, 2)` may or may not be the same + in two graphs) if you use MultiGraph without keeping track of edge keys. + + If combining the attributes of common nodes is not desired, consider union(), + which raises an exception for name collisions. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2)]) + >>> H = nx.Graph([(0, 1), (1, 2)]) + >>> R = nx.compose(G, H) + >>> R.nodes + NodeView((0, 1, 2)) + >>> R.edges + EdgeView([(0, 1), (0, 2), (1, 2)]) + + By default, the attributes from `H` take precedent over attributes from `G`. + If you prefer another way of combining attributes, you can update them after the compose operation: + + >>> G = nx.Graph([(0, 1, {"weight": 2.0}), (3, 0, {"weight": 100.0})]) + >>> H = nx.Graph([(0, 1, {"weight": 10.0}), (1, 2, {"weight": -1.0})]) + >>> nx.set_node_attributes(G, {0: "dark", 1: "light", 3: "black"}, name="color") + >>> nx.set_node_attributes(H, {0: "green", 1: "orange", 2: "yellow"}, name="color") + >>> GcomposeH = nx.compose(G, H) + + Normally, color attribute values of nodes of GcomposeH come from H. We can workaround this as follows: + + >>> node_data = { + ... n: G.nodes[n]["color"] + " " + H.nodes[n]["color"] + ... for n in G.nodes & H.nodes + ... } + >>> nx.set_node_attributes(GcomposeH, node_data, "color") + >>> print(GcomposeH.nodes[0]["color"]) + dark green + + >>> print(GcomposeH.nodes[3]["color"]) + black + + Similarly, we can update edge attributes after the compose operation in a way we prefer: + + >>> edge_data = { + ... e: G.edges[e]["weight"] * H.edges[e]["weight"] for e in G.edges & H.edges + ... } + >>> nx.set_edge_attributes(GcomposeH, edge_data, "weight") + >>> print(GcomposeH.edges[(0, 1)]["weight"]) + 20.0 + + >>> print(GcomposeH.edges[(3, 0)]["weight"]) + 100.0 + """ + return nx.compose_all([G, H]) + + +@nx._dispatchable(graphs=_G_H, preserve_all_attrs=True, returns_graph=True) +def full_join(G, H, rename=(None, None)): + """Returns the full join of graphs G and H. + + Full join is the union of G and H in which all edges between + G and H are added. + The node sets of G and H must be disjoint, + otherwise an exception is raised. + + Parameters + ---------- + G, H : graph + A NetworkX graph + + rename : tuple , 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". + + Returns + ------- + U : The full join graph with the same type as G. + + Notes + ----- + It is recommended that G and H be either both directed or both undirected. + + If G is directed, then edges from G to H are added as well as from H to G. + + Note that full_join() does not produce parallel edges for MultiGraphs. + + The full join operation of graphs G and H is the same as getting + their complement, performing a disjoint union, and finally getting + the complement of the resulting graph. + + Graph, edge, and node attributes are propagated from G and H + to the union graph. If a graph attribute is present in both + G and H the value from H is used. + + Examples + -------- + >>> G = nx.Graph([(0, 1), (0, 2)]) + >>> H = nx.Graph([(3, 4)]) + >>> R = nx.full_join(G, H, rename=("G", "H")) + >>> R.nodes + NodeView(('G0', 'G1', 'G2', 'H3', 'H4')) + >>> R.edges + EdgeView([('G0', 'G1'), ('G0', 'G2'), ('G0', 'H3'), ('G0', 'H4'), ('G1', 'H3'), ('G1', 'H4'), ('G2', 'H3'), ('G2', 'H4'), ('H3', 'H4')]) + + See Also + -------- + union + disjoint_union + """ + R = union(G, H, rename) + + def add_prefix(graph, prefix): + if prefix is None: + return graph + + def label(x): + return f"{prefix}{x}" + + return nx.relabel_nodes(graph, label) + + G = add_prefix(G, rename[0]) + H = add_prefix(H, rename[1]) + + for i in G: + for j in H: + R.add_edge(i, j) + if R.is_directed(): + for i in H: + for j in G: + R.add_edge(i, j) + + return R |