org.apache.solr.client.solrj.io.eval.MovingMedianEvaluator.java Source code

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Here is the source code for org.apache.solr.client.solrj.io.eval.MovingMedianEvaluator.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.solr.client.solrj.io.eval;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;
import org.apache.commons.math3.stat.descriptive.rank.Percentile;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

public class MovingMedianEvaluator extends RecursiveNumericEvaluator implements TwoValueWorker {
    protected static final long serialVersionUID = 1L;

    public MovingMedianEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
        super(expression, factory);
    }

    @Override
    public Object doWork(Object first, Object second) throws IOException {
        if (null == first) {
            throw new IOException(String.format(Locale.ROOT,
                    "Invalid expression %s - null found for the first value", toExpression(constructingFactory)));
        }
        if (null == second) {
            throw new IOException(String.format(Locale.ROOT,
                    "Invalid expression %s - null found for the second value", toExpression(constructingFactory)));
        }
        if (!(first instanceof List<?>)) {
            throw new IOException(String.format(Locale.ROOT,
                    "Invalid expression %s - found type %s for the first value, expecting a List",
                    toExpression(constructingFactory), first.getClass().getSimpleName()));
        }
        if (!(second instanceof Number)) {
            throw new IOException(String.format(Locale.ROOT,
                    "Invalid expression %s - found type %s for the second value, expecting a Number",
                    toExpression(constructingFactory), first.getClass().getSimpleName()));
        }

        List<?> values = (List<?>) first;
        int window = ((Number) second).intValue();

        List<Number> moving = new ArrayList<>();
        DescriptiveStatistics slider = new DescriptiveStatistics(window);
        Percentile percentile = new Percentile();
        for (Object value : values) {
            slider.addValue(((Number) value).doubleValue());
            if (slider.getN() >= window) {
                double median = percentile.evaluate(slider.getValues(), 50);
                moving.add(median);
            }
        }

        return moving;
    }

}