Graphlet degree vectors. (a) All 9 graphlets on 2, 3 and 4 nodes, denoted by G0, G1, ..., G8; they contain 15 topologically unique node types, called "automorphism orbits," denoted by 0, 1, 2 ..., 14. In a particular graphlet, nodes belonging to the same orbit are of the same shade . (b) An illustration of the "Graphlet Degree Vector" (GDV), or a "signature" of node v; coordinates of a GDV count how many times a node is touched by a particular automorphism orbit, such as an edge (the leftmost panel), a triangle (the middle panel), or a square (the rightmost panel). Hence, the degree is generalized to a GDV . The GDV of node v is presented in the table for orbits 0 to 14: v is touched by 5 edges (orbit 0), end-nodes of 2 graphlets G1(orbit 1), etc. Values of the 73 coordinates (for all of the 30 2-5-node graphlets) of the GDV of node v are presented in Additional file 1Figure S1.