Hi. I’m trying to use the spectrum function in iGraph for R. Spectrum(.) in its default form extracts the leading or maximum eigenvalue for a matrix. I want to use this eigenvalue to guide the choice of alpha in the alpha_centrality (.) function. In theory, an alpha that is less than the reciprocal of the leading eigenvalue of the matrix will yield meaningful values for the alpha centralities. But you need the leading eigenvalue first, and that’s where spectrum(.) comes in. (This is my latest attempt to use the alpha_centrality(.) function!)

Chalk this up to my inexperience, but how do you access the output from spectrum(.)? What is it called? Apparently, this output is a list, crypically referred to as containing three objects. I’m guessing that the objects are the input data frame, the leading eigenvalue, and the associated eigenvector. But what is the list called and how do I examine the output? I know how to print a list and objects within it.