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

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Here is the source code for org.apache.solr.client.solrj.io.eval.FindDelayEvaluator.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.math.BigDecimal;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;

import org.apache.commons.math3.util.MathArrays;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

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

    public FindDelayEvaluator(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 of numbers",
                    toExpression(constructingFactory), first.getClass().getSimpleName()));
        }
        if (!(second instanceof List<?>)) {
            throw new IOException(String.format(Locale.ROOT,
                    "Invalid expression %s - found type %s for the second value, expecting a list of numbers",
                    toExpression(constructingFactory), first.getClass().getSimpleName()));
        }

        // Get first and second lists as arrays, where second is in reverse order
        double[] firstArray = ((List) first).stream().mapToDouble(value -> ((BigDecimal) value).doubleValue())
                .toArray();
        double[] secondArray = StreamSupport
                .stream(Spliterators.spliteratorUnknownSize(
                        ((LinkedList) ((List) second).stream().collect(Collectors.toCollection(LinkedList::new)))
                                .descendingIterator(),
                        Spliterator.ORDERED), false)
                .mapToDouble(value -> ((BigDecimal) value).doubleValue()).toArray();

        double[] convolution = MathArrays.convolve(firstArray, secondArray);
        double maxValue = -Double.MAX_VALUE;
        double indexOfMaxValue = -1;

        for (int idx = 0; idx < convolution.length; ++idx) {
            double abs = Math.abs(convolution[idx]);
            if (abs > maxValue) {
                maxValue = abs;
                indexOfMaxValue = idx;
            }
        }

        return (indexOfMaxValue + 1) - secondArray.length;

    }
}