Partitions a collection into groups based on a characteristics of that group. - Java java.util

Java examples for java.util:Collection Operation

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Description

Partitions a collection into groups based on a characteristics of that group.

Demo Code

/*//from w  ww .  j a  va  2 s  .c om
 * The MIT License
 *
 * Copyright (c) 2010 The Broad Institute
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
import java.util.*;

public class Main{
    /** 
     * Partitions a collection into groups based on a characteristics of that group.  Partitions are embodied in a map, whose keys are the
     * value of that characteristic, and the values are the partition of elements whose characteristic evaluate to that key.
     */
    public static <K, V> Map<K, Collection<V>> partition(
            final Collection<V> collection, final Partitioner<V, K> p) {
        final MultiMap<K, V> partitionToValues = new MultiMap<K, V>();
        for (final V entry : collection) {
            partitionToValues.append(p.getPartition(entry), entry);
        }
        return partitionToValues;
    }
}

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