cache_edge_count_ws: Cache a count of edges (available in a
selection) in the graph
Description
From a graph object of class
dgr_graph, get a count of edges available in
a selection and cache that value in the graph for
later retrieval using get_cache.
Usage
cache_edge_count_ws(graph)
Arguments
graph
a graph object of class
dgr_graph that is created using
create_graph.