This function calculates rapidly AUCs based on an approximation: the
fraction of iters random (positive, negative) pairs, drawn with
replacement, where the positive score is larger.
Usage
rs_fast_auc(pos_scores, neg_scores, iters, seed)
Arguments
pos_scores
The scores of your hits.
neg_scores
The scores of your non-hits.
iters
Number of iterations to run the function for.
Recommended size: 10000L.