Use this if you are using igraph from R
cliques {igraph}  R Documentation 
These functions find all, the largest or all the maximal cliques in an undirected graph. The size of the largest clique can also be calculated.
cliques(graph, min = 0, max = 0)
max_cliques(graph, min = NULL, max = NULL, subset = NULL, file = NULL)
graph 
The input graph, directed graphs will be considered as undirected ones, multiple edges and loops are ignored. 
min 
Numeric constant, lower limit on the size of the cliques to find.

max 
Numeric constant, upper limit on the size of the cliques to find.

subset 
If not 
file 
If not 
cliques
find all complete subgraphs in the input graph, obeying the
size limitations given in the min
and max
arguments.
largest_cliques
finds all largest cliques in the input graph. A
clique is largest if there is no other clique including more vertices.
max_cliques
finds all maximal cliques in the input graph. A
clique is maximal if it cannot be extended to a larger clique. The largest
cliques are always maximal, but a maximal clique is not necessarily the
largest.
count_max_cliques
counts the maximal cliques.
clique_num
calculates the size of the largest clique(s).
clique_size_counts
returns a numeric vector representing a histogram
of clique sizes, between the given minimum and maximum clique size.
cliques
, largest_cliques
and clique_num
return a list containing numeric vectors of vertex ids. Each list element is
a clique, i.e. a vertex sequence of class igraph.vs
.
max_cliques
returns NULL
, invisibly, if its file
argument is not NULL
. The output is written to the specified file in
this case.
clique_num
and count_max_cliques
return an integer
scalar.
clique_size_counts
returns a numeric vector with the clique sizes such that
the ith item belongs to cliques of size i. Trailing zeros are currently
truncated, but this might change in future versions.
Tamas Nepusz ntamas@gmail.com and Gabor Csardi csardi.gabor@gmail.com
For maximal cliques the following algorithm is implemented: David Eppstein, Maarten Loffler, Darren Strash: Listing All Maximal Cliques in Sparse Graphs in Nearoptimal Time. https://arxiv.org/abs/1006.5440
# this usually contains cliques of size six
g < sample_gnp(100, 0.3)
clique_num(g)
cliques(g, min=6)
largest_cliques(g)
# To have a bit less maximal cliques, about 100200 usually
g < sample_gnp(100, 0.03)
max_cliques(g)