Method size

networkx/classes/graph.py:1918–1959

Returns the number of edges or total of all edge weights. Parameters ---------- 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. Returns

(self, weight=None)

        return nx.edge_subgraph(self, edges)

    def size(self, weight=None):
        """Returns the number of edges or total of all edge weights.

        Parameters
        ----------
        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.

        Returns
        -------
        size : numeric
            The number of edges or
            (if weight keyword is provided) the total weight sum.

            If weight is None, returns an int. Otherwise a float
            (or more general numeric if the weights are more general).

        See Also
        --------
        number_of_edges

        Examples
        --------
        >>> G = nx.path_graph(4)  # or DiGraph, MultiGraph, MultiDiGraph, etc
        >>> G.size()
        3

        >>> G = nx.Graph()  # or DiGraph, MultiGraph, MultiDiGraph, etc
        >>> G.add_edge("a", "b", weight=2)
        >>> G.add_edge("b", "c", weight=4)
        >>> G.size()
        2
        >>> G.size(weight="weight")
        6.0
        """
        s = sum(d for v, d in self.degree(weight=weight))
        # If `weight` is None, the sum of the degrees is guaranteed to be
        # even, so we can perform integer division and hence return an
        # integer. Otherwise, the sum of the weighted degrees is not
        # guaranteed to be an integer, so we perform "real" division.
        return s // 2 if weight is None else s / 2

    def number_of_edges(self, u=None, v=None):
        """Returns the number of edges between two nodes.