Wishlist: Better interface for contracting vertices

szhorvat commented 9 months ago

What is the feature or improvement you would like to see?

igraph_contract_vertices() requires a mapping as input. This is almost always inconvenient. There should be alternative interfaces to contraction that:

Take groups of vertices to be contracted together, and return the new graph along with a mapping between indices
Take an edge as input and contract its endpoints, while removing the edge. The usual definition of edge contraction also includes the removal of the edge, which contract_vertices() would not do.
Take a set of edges and contract their endpoints. This would allow contracting paths as well.

Use cases for the feature

The proposed interfaces fit most graph theory applications better.

References —

elena-schafer commented 7 months ago

Is anyone working on this? If not I'd like to.

szhorvat commented 7 months ago

@EdgarAlenPoe Let's finish your blossom algorithm pull requests before starting with another project.

igraph / igraph

Wishlist: Better interface for contracting vertices #2465