Fig. 6

Example public transport multiplex network with \(L=3\) selected layers of Freiburg (corresponding to two tram layers and one bus layer) and \(n=126\) stops. The graphics were created with the python package pymnet (Kivelä 2017). Left: Visualization of the multiplex network. Intra-layer edges are marked dark blue and inter-layer edges are marked red. Right: Sparsity structure of the corresponding supra-adjacency matrix. Dark blue entries represent intra-layer edges and red entries represent inter-layer edges