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OptaPlanner solves planning problems. This lightweight, embeddable planning engine implements powerful and scalable algorithms to optimize business resource scheduling and planning. This module contains the examples which demonstrate how to use it in a normal Java application.

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/*
 * Copyright 2018 Red Hat, Inc. and/or its affiliates.
 *
 * 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 org.optaplanner.examples.common.persistence.generator;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class ProbabilisticDataGenerator {

    public static  E extractRandomElement(Random random, List list) {
        return list.get(random.nextInt(list.size()));
    }

    public static  List extractRandomSubList(Random random, List list, double... thresholds) {
        int size = generateRandomIntFromThresholds(random, thresholds);
        if (size > list.size()) {
            size = list.size();
        }
        return extractRandomSubListOfSize(random, list, size);
    }

    public static  List extractRandomSubListOfSize(Random random, List list, int size) {
        List subList = new ArrayList<>(list);
        Collections.shuffle(subList, random);
        // Remove elements not in the sublist (so it can be garbage collected)
        subList.subList(size, subList.size()).clear();
        return subList;
    }

    public static int generateRandomIntFromThresholds(Random random, double... thresholds) {
        double randomDouble = random.nextDouble();
        for (int i = 0; i < thresholds.length; i++) {
            if (randomDouble < thresholds[i]) {
                return i;
            }
        }
        return thresholds.length;
    }

    private ProbabilisticDataGenerator() {
    }

}