Extracting subgraph from Heterograph

[GianlucaDeStefano]

Hi all,

My task is simple; given an edge in an heterograph, I want to extract its neighborhood graph up to a certain number of hops.

Looking at the documentation, I have yet to find a good way to do this.
I found the utility k_hop_subgraph, but unfortunately, it does not support HeteroGraphs.

Exploring the code of Pyg found that /sampler/init.py contains the function "hetero_neighbor_sample" that is, however, undocumented. Can someone please clarify to me the difference between the parameters:

    rowptr_dict: Dict[EdgeType, Tensor],
    col_dict: Dict[EdgeType, Tensor]

In practice, what should they contain?
is there maybe a better function to use that I have missed?

[wsad1]

A hacky way of doing this would be to use the LinkNeighborLoader.

loader = LinkNeighborLoader( data = your_data, num_neighbors = [-1]*num_hops, edge_label_index = ((edge_type), edge_index))
subgraph = next(iter(loader))

Given this is hacky. It would be nice to have k_hop_subgraph support heterogenous graphs.

[rusty1s]

Second this. Currently, the most efficient way is to utilize the NeighborLoader classes for this. If you want to start sampling from nodes rather than links, you can also use NeighborLoader rather than LinkNeighborLoader.