Thanks for the reply. Response to your suggestions below. On Feb 26, 1:21 pm, David Joyner <wdjoy...@gmail.com> wrote: > ...snip... > > > I considered another option. Why not just wait until an edge is added > > to figure out whether a node is left or right? Because all the > > vertices should be in one set or the other at all times. For example, > > if I add a vertex and then iterate (before adding any edges) over the > > left and right subsets, the new vertex would be absent! > > It seems you are suggesting that there should be 2 ways to > add a vertex to a bipartite graph. Either add_vertex with a > required parameter specifying which vertex set to add it to, or > using add_edge? I don't see a problem off-hand.
Let me clarify my suggestion. add_vertex could have a "limbo" set -- neither left nor right -- and nodes could be moved from "limbo" to the appropriate set when an edge is added. In short, we know what set a node should be in once it has an edge, but not immediately upon adding it. Allowing add_edge to also create the node is interesting, but doesn't solve the problem of what to do when add_vertex is called with insufficient information. > > A. Change BipartiteGraph so that it doesn't inherit from Graph. This > > requires adding a bunch of code to bring the BipartiteGraph > > functionality to par with Graph. Also, any future methods added to > > Graph will need to be duplicated (often simply delegated) in > > BipartiteGraph. > > I personally favor this as it seems to me (and I definitely could > be wrong) that the code will be more readable in this case. > If every method in graph.py must test if the graph is bipartite > or not, that makes it more difficult read and more difficult to debug, IMHO. Yes, this is the purest approach. On the other hand, a large fraction of the Graph methods will work *unchanged* for BipartiteGraph instances. And the vast majority of those that do need changes require only minor adjustments. Personally, adding a little extra code to (Generic)Graph is preferable to duplicating lots of code (and possible bugs) in BipartiteGraph. Thanks for your opinion! - Ryan -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
