kagle Elo Merchant Category Recommendation 21th solution rank 21/4200 single model single model: lb 3.680 3.677 3.679 stacking: lb 3.669 pb 3.601 features: 1 agg features 2 +-*/ new agg features and history agg faeatures 3 date features 4 counter vector features 5 nn features 6 word2vec features