org.apache.predictionio.examples.java.recommendations.tutorial3.Evaluator.java Source code

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Here is the source code for org.apache.predictionio.examples.java.recommendations.tutorial3.Evaluator.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.predictionio.examples.java.recommendations.tutorial3;

import org.apache.predictionio.examples.java.recommendations.tutorial1.Query;
import org.apache.predictionio.controller.java.JavaEvaluator;
import org.apache.predictionio.controller.java.EmptyParams;

import scala.Tuple2;
import java.util.Arrays;
import org.apache.commons.collections.IteratorUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** Root mean square error */
public class Evaluator extends JavaEvaluator<EmptyParams, Object, Query, Float, Float, Double, Double, String> {

    final static Logger logger = LoggerFactory.getLogger(Evaluator.class);

    @Override
    public Double evaluateUnit(Query query, Float predicted, Float actual) {
        logger.info("Q: " + query.toString() + " P: " + predicted + " A: " + actual);
        // return squared error
        double error;
        if (predicted.isNaN())
            error = -actual;
        else
            error = predicted - actual;
        return (error * error);
    }

    @Override
    public Double evaluateSet(Object dataParams, Iterable<Double> metricUnits) {
        double sum = 0.0;
        int count = 0;
        for (double squareError : metricUnits) {
            sum += squareError;
            count += 1;
        }
        return Math.sqrt(sum / count);
    }

    @Override
    public String evaluateAll(Iterable<Tuple2<Object, Double>> input) {
        return Arrays.toString(IteratorUtils.toArray(input.iterator()));
    }
}