Triad census, subgraphs with three vertices
This function counts the different subgraphs of three vertices in a graph.
- The input graph, it should be directed. An undirected graph results a warning, and undefined results.
Triad census was defined by David and Leinhardt (see References below). Every triple of vertices (A, B, C) are classified into the 16 possible states:
- A numeric vector, the subgraph counts, in the order given in the above description.
See also Davis, J.A. and Leinhardt, S. (1972). The Structure of Positive Interpersonal Relations in Small Groups. In J. Berger (Ed.), Sociological Theories in Progress, Volume 2, 218-251. Boston: Houghton Mifflin.
g <- erdos.renyi.game(15, 45, type="gnm", dir=TRUE) triad.census(g)