/**
* Get a random buyer UserId, where the probability that a particular user is selected increases
* based on the number of bids that they have made in the past. We won't allow the last bidder to
* be selected again
*
* @param previousBidders
* @return
*/
public UserId getRandomBuyerId(Histogram<UserId> previousBidders, UserId... exclude) {
// This is very inefficient, but it's probably good enough for now
tmp_userIdHistogram.clear();
tmp_userIdHistogram.putHistogram(previousBidders);
for (UserId ex : exclude) tmp_userIdHistogram.removeAll(ex);
tmp_userIdHistogram.put(this.getRandomBuyerId(exclude));
try {
LOG.trace("New Histogram:\n" + tmp_userIdHistogram);
} catch (NullPointerException ex) {
for (UserId user_id : tmp_userIdHistogram.values()) {
System.err.println(
String.format(
"%s => NEW:%s / ORIG:%s",
user_id, tmp_userIdHistogram.get(user_id), previousBidders.get(user_id)));
}
throw ex;
}
FlatHistogram<UserId> rand_h = new FlatHistogram<UserId>(rng, tmp_userIdHistogram);
return (rand_h.nextValue());
}
public int getRandomCategoryId() {
if (this.randomCategory == null) {
this.randomCategory = new FlatHistogram<Integer>(this.rng, this.items_per_category);
}
return randomCategory.nextInt();
}