001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.data;
031
032import java.lang.reflect.Array;
033import java.util.Iterator;
034import java.util.Random;
035
036import org.openimaj.util.array.ArrayIterator;
037
038/**
039 * A {@link DataSource} backed by an array.
040 *
041 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
042 * @param <T>
043 *            Type of object
044 *
045 */
046public abstract class ArrayBackedDataSource<T> implements DataSource<T> {
047        protected T[] data;
048        protected Random rng;
049
050        /**
051         * Construct with data
052         *
053         * @param data
054         *            the data
055         */
056        public ArrayBackedDataSource(T[] data) {
057                this.data = data;
058                this.rng = new Random();
059        }
060
061        /**
062         * Construct with data and a random generator for random sampling
063         *
064         * @param data
065         *            the data
066         * @param rng
067         *            the random generator
068         */
069        public ArrayBackedDataSource(T[] data, Random rng) {
070                this.data = data;
071                this.rng = rng;
072        }
073
074        @Override
075        public final void getData(int startRow, int stopRow, T[] output) {
076                for (int i = startRow, j = 0; i < stopRow; i++, j++)
077                        output[j] = data[i];
078        }
079
080        @Override
081        public final void getRandomRows(T[] output) {
082                final int k = output.length;
083                final int[] ind = RandomData.getUniqueRandomInts(k, 0, data.length, rng);
084
085                for (int i = 0; i < k; i++)
086                        output[i] = data[ind[i]];
087        }
088
089        @Override
090        public int size() {
091                return data.length;
092        }
093
094        @Override
095        public T getData(int row) {
096                return data[row];
097        }
098
099        @Override
100        public Iterator<T> iterator() {
101                return new ArrayIterator<T>(data);
102        }
103
104        @SuppressWarnings("unchecked")
105        @Override
106        public T[] createTemporaryArray(int size) {
107                return (T[]) Array.newInstance(data.getClass().getComponentType(), size);
108        }
109}