Read a network from common file formats into a netify object
Source:R/read_external.R
read_external.Rdthin wrappers around igraph::read_graph() for the formats users
coming from gephi / pajek / networkx most often hand over (graphml,
pajek .net, gml). each reader loads the file via igraph and
immediately runs netify() on the result so the user gets a
netify back in one call, with edge weights auto-detected and
directedness preserved.