Method to_undirected

easygraph/classes/directed_multigraph.py:326–393

Returns an undirected representation of the multidigraph. Parameters ---------- reciprocal : bool (optional) If True only keep edges that appear in both directions in the original digraph. Returns ------- G : MultiGraph

(self, reciprocal=False)

        return True

    def to_undirected(self, reciprocal=False):
        """Returns an undirected representation of the multidigraph.

        Parameters
        ----------
        reciprocal : bool (optional)
          If True only keep edges that appear in both directions
          in the original digraph.

        Returns
        -------
        G : MultiGraph
            An undirected graph with the same name and nodes and
            with edge (u, v, data) if either (u, v, data) or (v, u, data)
            is in the digraph.  If both edges exist in digraph and
            their edge data is different, only one edge is created
            with an arbitrary choice of which edge data to use.
            You must check and correct for this manually if desired.

        See Also
        --------
        MultiGraph, add_edge, add_edges_from

        Notes
        -----
        This returns a "deepcopy" of the edge, node, and
        graph attributes which attempts to completely copy
        all of the data and references.

        This is in contrast to the similar D=MultiDiGraph(G) which
        returns a shallow copy of the data.

        See the Python copy module for more information on shallow
        and deep copies, https://docs.python.org/3/library/copy.html.

        Warning: If you have subclassed MultiDiGraph to use dict-like
        objects in the data structure, those changes do not transfer
        to the MultiGraph created by this method.

        Examples
        --------
        >>> G = eg.path_graph(2)  # or MultiGraph, etc
        >>> H = G.to_directed()
        >>> list(H.edges)
        [(0, 1), (1, 0)]
        >>> G2 = H.to_undirected()
        >>> list(G2.edges)
        [(0, 1)]
        """
        G = eg.MultiGraph()
        G.graph.update(deepcopy(self.graph))
        G.add_nodes_from((n, deepcopy(d)) for n, d in self._node.items())
        if reciprocal is True:
            G.add_edges_from(
                (u, v, key, deepcopy(data))
                for u, nbrs in self._adj.items()
                for v, keydict in nbrs.items()
                for key, data in keydict.items()