On Wed, 12 Oct 2011, Shaun Jackman wrote:

Hi,

I have a directed acyclic word graph (DAWG) [1] for which the fundamentally efficient operation takes a vertex descriptor and an edge label and returns an edge descriptor (if that edge exists). An out_edge_iterator can be used to iterate over the edges to find the edge with the specified label, but it's not very efficient. I plan to extend the BGL API to add the needed functionality. I wanted to check first that this function doesn't already exist, and if it doesn't, ask for suggested names. I was thinking of...

pair<edge_descriptor, bool> out_edge( vertex_descriptor u, edge_label i, Graph g);

The type of edge_label would depend on the graph. For me, it's a char.

This sort of labelled edge navigation also applies to a de Bruijn graph [2].

There is a function in BGL called edge(); it is officially a part of the Adjacency Matrix concept but is implemented for many more graph types (with higher than Adjacency Matrix' required complexity). Perhaps your function should be "edge_by_label" or something? Also, are you considering having an equivalent to edge_range for labeled edges as well (it is important for graphs with parallel edges, and so a fully general concept should probably have it)? The function in named_graph is called find_vertex, so that could be some inspiration for your name; that class also has vertex_by_property. Do you intend this to be a more general mechanism for other properties, or just for some kind of edge name or label? -- Jeremiah Willcock