Randomly select records given a probability weight vector prob.
NOTE: This is an internal function used for testing the C++-function randSample which is used inside the C++-function recordSwap().
randSample_cpp(ID, N, prob, IDused, seed)vector containing record IDs from which to sample
integer defining the number of records to be sampled
a vector of probability weights for obtaining the elements of the vector being sampled.
vector containing IDs which must not be sampled
integer setting the sampling seed