How to understand the shape of "nbr_fea_idx" in the code

[Powerd0g]

I couldn't understand "the indices of M neighbors of each atom"
Could you give me a simple example about the matrix of "nbr_fea_idx".
Thank you!

[txie-93]

Thanks for your question. nbr_fea_idx is the indices of the M neighbors for each node. For instance, you have two nodes 0 and 1. Each node is connected to the other and has one neighbor. In this case, M = 1 and nbr_fea_idx = [[1], [0]].

[Powerd0g]

Thanks for your answer.
if node 0 is connected to a new node 2, but node 1 is not. In this case, what M and nbr_fea_idx look like?