Use this if you are using igraph from R
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))
graph |
The input graph. It might be directed, but edge directions are ignored. |
vids |
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.
For triangles
a numeric vector of vertex ids, the first three
vertices belong to the first triangle found, etc.
For count_triangles
a numeric vector, the number of triangles for all
vertices queried.
Gabor Csardi csardi.gabor@gmail.com
## 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)