Find triangles in graphs
Count how many triangles a vertex is part of, in a graph, or just list the triangles of a graph.
count_triangles(graph, vids = V(graph))
- The input graph. It might be directed, but edge directions are ignored.
- The vertices to query, all of them by default. This might be a vector of numeric ids, or a character vector of symbolic vertex names for named graphs.
triangles lists all triangles of a graph. For efficiency, all
triangles are returned in a single vector. The first three vertices belong
to the first triangle, etc.
count_triangles counts how many triangles a vertex is part of.
trianglesa numeric vector of vertex ids, the first three vertices belong to the first triangle found, etc.
trianglesa numeric vector, the number of triangles for all vertices queried.
## A small graph kite <- make_graph("Krackhardt_Kite") plot(kite) matrix(triangles(kite), nrow=3) ## Adjacenct triangles atri <- count_triangles(kite) plot(kite, vertex.label=atri) ## Always true sum(count_triangles(kite)) == length(triangles(kite)) ## Should match, local transitivity is the ## number of adjacent triangles divided by the number ## of adjacency triples transitivity(kite, type="local") count_triangles(kite) / (degree(kite) * (degree(kite)-1)/2)