I am trying to use graph-tool to study the assortativity of certain graphs. I find that there are two functions in graph-tool that would do the job: "gt.assortativity" and "gt.scalar_assortativity". I initially thought that if the scalar property that I am interested in is the degree itself, I would get the same value for both. But I don't!

I tried calculating assortativity for simple undirected Erdos-Renyi graphs and only "scalar assortativity" seems to give correct answer. In fact, "gt.assortativity" gives me quite high values even for ER graphs. Can somebody kindly explain the problem?