Random parent vector
.RandomParent(n, seed = sample.int(2147483647L, 1L))Integer specifying number of leaves.
(Optional) Integer with which to seed Mersenne Twister random number generator in C++.
Integer vector corresponding to the 'parent' entry of tree$edge,
where the 'child' entry, i.e. column 2, is numbered sequentially from 1:n.