graph coarsening methods don't work

[RRRussell]

The source code uses sfdp library for graph coarsening.
But when I tried these three standard datasets, I found that the graph was not coarsened.
That is, after the sentence "recursive_graphs, recursive_merged_nodes = [], read_coarsening_info( temp_dir)" of the external_ec_coarsening() function in graph_coarsening.py, the recursive_merged_nodes I received is an empty list.
I want to know what happened because this caused the external_ec_coarsening() function to directly return the original graph.

[GTmac]

I have just replied your email -- let's follow us there :)