Description of the count pairs function.
count_pairs(a, b, order)a list of five different vectors:
pair_nb: a vector containing counts of nodes within all possible
classification pairs from partitions a and b
pair_a: a vector of the same length as pair_nb, specifying the order
of classifications in pair_nb from partition a
pair_b: a vector of the same length as pair_nb, specifying the order
of classifications in pair_nb from partition b
a_nb: a vector containing counts of nodes within each class for
partition a
b_nb: a vector containing counts of nodes within each class for
partition b
a vector of classifications
a vector of classifications
a vector of permutations (coming from the order() function in base R)
A function to count pairs of integers or factors and identify the pair counts