Fixed catastrophic hash collisions in
FreqTable::make_hash and vecHasher: hashes of
small-integer statistics had no entropy in their low bits, so
std::unordered_map placed (nearly) all keys in a single
bucket, making support computation O(4^ncol) instead of O(2^ncol).
Models with many response columns (e.g., 16) appeared to hang during
initialization (USCbiostats/barry#24).
FreqTable::add() now verifies the stored row on a
hash hit and keeps true 64-bit hash collisions in a per-hash overflow
chain, so distinct statistics can no longer be silently merged
(USCbiostats/barry#24).
barry’s
versioning.