Fixed database typo and removed unnecessary class identifier.

venv/share/doc/networkx-2.5/examples/subclass/README.txt

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+Subclass
+--------

venv/share/doc/networkx-2.5/examples/subclass/plot_antigraph.py

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+"""
+=========
+Antigraph
+=========
+
+Complement graph class for small footprint when working on dense graphs.
+
+This class allows you to add the edges that *do not exist* in the dense
+graph. However, when applying algorithms to this complement graph data
+structure, it behaves as if it were the dense version. So it can be used
+directly in several NetworkX algorithms.
+
+This subclass has only been tested for k-core, connected_components,
+and biconnected_components algorithms but might also work for other
+algorithms.
+
+"""
+import networkx as nx
+from networkx.exception import NetworkXError
+import matplotlib.pyplot as plt
+
+
+class AntiGraph(nx.Graph):
+    """
+    Class for complement graphs.
+
+    The main goal is to be able to work with big and dense graphs with
+    a low memory footprint.
+
+    In this class you add the edges that *do not exist* in the dense graph,
+    the report methods of the class return the neighbors, the edges and
+    the degree as if it was the dense graph. Thus it's possible to use
+    an instance of this class with some of NetworkX functions.
+    """
+
+    all_edge_dict = {"weight": 1}
+
+    def single_edge_dict(self):
+        return self.all_edge_dict
+
+    edge_attr_dict_factory = single_edge_dict
+
+    def __getitem__(self, n):
+        """Return a dict of neighbors of node n in the dense graph.
+
+        Parameters
+        ----------
+        n : node
+           A node in the graph.
+
+        Returns
+        -------
+        adj_dict : dictionary
+           The adjacency dictionary for nodes connected to n.
+
+        """
+        return {
+            node: self.all_edge_dict for node in set(self.adj) - set(self.adj[n]) - {n}
+        }
+
+    def neighbors(self, n):
+        """Return an iterator over all neighbors of node n in the
+           dense graph.
+
+        """
+        try:
+            return iter(set(self.adj) - set(self.adj[n]) - {n})
+        except KeyError as e:
+            raise NetworkXError(f"The node {n} is not in the graph.") from e
+
+    def degree(self, nbunch=None, weight=None):
+        """Return an iterator for (node, degree) in the dense graph.
+
+        The node degree is the number of edges adjacent to the node.
+
+        Parameters
+        ----------
+        nbunch : iterable container, optional (default=all nodes)
+            A container of nodes.  The container will be iterated
+            through once.
+
+        weight : string or None, optional (default=None)
+           The edge attribute that holds the numerical value used
+           as a weight.  If None, then each edge has weight 1.
+           The degree is the sum of the edge weights adjacent to the node.
+
+        Returns
+        -------
+        nd_iter : iterator
+            The iterator returns two-tuples of (node, degree).
+
+        See Also
+        --------
+        degree
+
+        Examples
+        --------
+        >>> G = nx.path_graph(4)  # or DiGraph, MultiGraph, MultiDiGraph, etc
+        >>> list(G.degree(0))  # node 0 with degree 1
+        [(0, 1)]
+        >>> list(G.degree([0, 1]))
+        [(0, 1), (1, 2)]
+
+        """
+        if nbunch is None:
+            nodes_nbrs = (
+                (
+                    n,
+                    {
+                        v: self.all_edge_dict
+                        for v in set(self.adj) - set(self.adj[n]) - {n}
+                    },
+                )
+                for n in self.nodes()
+            )
+        elif nbunch in self:
+            nbrs = set(self.nodes()) - set(self.adj[nbunch]) - {nbunch}
+            return len(nbrs)
+        else:
+            nodes_nbrs = (
+                (
+                    n,
+                    {
+                        v: self.all_edge_dict
+                        for v in set(self.nodes()) - set(self.adj[n]) - {n}
+                    },
+                )
+                for n in self.nbunch_iter(nbunch)
+            )
+
+        if weight is None:
+            return ((n, len(nbrs)) for n, nbrs in nodes_nbrs)
+        else:
+            # AntiGraph is a ThinGraph so all edges have weight 1
+            return (
+                (n, sum((nbrs[nbr].get(weight, 1)) for nbr in nbrs))
+                for n, nbrs in nodes_nbrs
+            )
+
+    def adjacency_iter(self):
+        """Return an iterator of (node, adjacency set) tuples for all nodes
+           in the dense graph.
+
+        This is the fastest way to look at every edge.
+        For directed graphs, only outgoing adjacencies are included.
+
+        Returns
+        -------
+        adj_iter : iterator
+           An iterator of (node, adjacency set) for all nodes in
+           the graph.
+
+        """
+        for n in self.adj:
+            yield (n, set(self.adj) - set(self.adj[n]) - {n})
+
+
+# Build several pairs of graphs, a regular graph
+# and the AntiGraph of it's complement, which behaves
+# as if it were the original graph.
+Gnp = nx.gnp_random_graph(20, 0.8, seed=42)
+Anp = AntiGraph(nx.complement(Gnp))
+Gd = nx.davis_southern_women_graph()
+Ad = AntiGraph(nx.complement(Gd))
+Gk = nx.karate_club_graph()
+Ak = AntiGraph(nx.complement(Gk))
+pairs = [(Gnp, Anp), (Gd, Ad), (Gk, Ak)]
+# test connected components
+for G, A in pairs:
+    gc = [set(c) for c in nx.connected_components(G)]
+    ac = [set(c) for c in nx.connected_components(A)]
+    for comp in ac:
+        assert comp in gc
+# test biconnected components
+for G, A in pairs:
+    gc = [set(c) for c in nx.biconnected_components(G)]
+    ac = [set(c) for c in nx.biconnected_components(A)]
+    for comp in ac:
+        assert comp in gc
+# test degree
+for G, A in pairs:
+    node = list(G.nodes())[0]
+    nodes = list(G.nodes())[1:4]
+    assert G.degree(node) == A.degree(node)
+    assert sum(d for n, d in G.degree()) == sum(d for n, d in A.degree())
+    # AntiGraph is a ThinGraph, so all the weights are 1
+    assert sum(d for n, d in A.degree()) == sum(d for n, d in A.degree(weight="weight"))
+    assert sum(d for n, d in G.degree(nodes)) == sum(d for n, d in A.degree(nodes))
+
+nx.draw(Gnp)
+plt.show()

venv/share/doc/networkx-2.5/examples/subclass/plot_printgraph.py

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+"""
+===========
+Print Graph
+===========
+
+Example subclass of the Graph class.
+"""
+
+import matplotlib.pyplot as plt
+import networkx as nx
+from networkx import Graph
+
+
+class PrintGraph(Graph):
+    """
+    Example subclass of the Graph class.
+
+    Prints activity log to file or standard output.
+    """
+
+    def __init__(self, data=None, name="", file=None, **attr):
+        Graph.__init__(self, data=data, name=name, **attr)
+        if file is None:
+            import sys
+
+            self.fh = sys.stdout
+        else:
+            self.fh = open(file, "w")
+
+    def add_node(self, n, attr_dict=None, **attr):
+        Graph.add_node(self, n, attr_dict=attr_dict, **attr)
+        self.fh.write(f"Add node: {n}\n")
+
+    def add_nodes_from(self, nodes, **attr):
+        for n in nodes:
+            self.add_node(n, **attr)
+
+    def remove_node(self, n):
+        Graph.remove_node(self, n)
+        self.fh.write(f"Remove node: {n}\n")
+
+    def remove_nodes_from(self, nodes):
+        for n in nodes:
+            self.remove_node(n)
+
+    def add_edge(self, u, v, attr_dict=None, **attr):
+        Graph.add_edge(self, u, v, attr_dict=attr_dict, **attr)
+        self.fh.write(f"Add edge: {u}-{v}\n")
+
+    def add_edges_from(self, ebunch, attr_dict=None, **attr):
+        for e in ebunch:
+            u, v = e[0:2]
+            self.add_edge(u, v, attr_dict=attr_dict, **attr)
+
+    def remove_edge(self, u, v):
+        Graph.remove_edge(self, u, v)
+        self.fh.write(f"Remove edge: {u}-{v}\n")
+
+    def remove_edges_from(self, ebunch):
+        for e in ebunch:
+            u, v = e[0:2]
+            self.remove_edge(u, v)
+
+    def clear(self):
+        Graph.clear(self)
+        self.fh.write("Clear graph\n")
+
+
+G = PrintGraph()
+G.add_node("foo")
+G.add_nodes_from("bar", weight=8)
+G.remove_node("b")
+G.remove_nodes_from("ar")
+print("Nodes in G: ", G.nodes(data=True))
+G.add_edge(0, 1, weight=10)
+print("Edges in G: ", G.edges(data=True))
+G.remove_edge(0, 1)
+G.add_edges_from(zip(range(0, 3), range(1, 4)), weight=10)
+print("Edges in G: ", G.edges(data=True))
+G.remove_edges_from(zip(range(0, 3), range(1, 4)))
+print("Edges in G: ", G.edges(data=True))
+
+G = PrintGraph()
+nx.add_path(G, range(10))
+nx.add_star(G, range(9, 13))
+nx.draw(G)
+plt.show()