FFMPredictUDAF.java

/*
 * Hivemall: Hive scalable Machine Learning Library
 *
 * Copyright (C) 2015 Makoto YUI
 * Copyright (C) 2013-2015 National Institute of Advanced Industrial Science and Technology (AIST)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package hivemall.fm;

import javax.annotation.Nullable;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.AggregationBuffer;

@Description(name = "ffm_predict",
        value = "_FUNC_(double Wi, array<float> Vi, array<float> Vj, double Xi, double Xj)"
                + " - Returns a prediction value in Double")
public final class FFMPredictUDAF {

    public static class FFMPredictAggregationBuffer implements AggregationBuffer {

        private double ret = 0.d;

        private void merge(final double w0) {
            ret += w0;
        }

        private void merge(final double Wi, @Nullable final float[] Vij,
                @Nullable final float[] Vji, final double Xi, final double Xj, final int factors) {
            ret += Xi * Wi;
            for (int f = 0; f < factors; f++) {
                ret += Vij[f] * Vji[f] * Xi * Xj;
            }
        }

    }

}