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
032/**
033 * This {@link DataSource} provides randomly sampled view over another
034 * {@link DataSource}.
035 * 
036 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
037 * 
038 * @param <DATATYPE>
039 *            the data type which can be returned
040 */
041public class RandomSampleDataSource<DATATYPE> extends IndexedViewDataSource<DATATYPE> {
042
043        /**
044         * Construct the view over the given {@link DataSource} such that it has
045         * requestedSize items.
046         * 
047         * @param dataSource
048         *            the dataSource to sample
049         * @param requestedSize
050         *            the requested number of rows
051         * 
052         * @throws IllegalArgumentException
053         *             if the requested size is bigger than the number of rows in
054         *             the datasource being sampled, or less than one.
055         */
056        public RandomSampleDataSource(DataSource<DATATYPE> dataSource, int requestedSize) {
057                super(dataSource, RandomData.getUniqueRandomInts(requestedSize, 0, dataSource.size()));
058        }
059
060        /**
061         * Construct the view over the given {@link DataSource} such that it has the
062         * given proportion of items from the original.
063         * 
064         * @param dataSource
065         *            the dataSource to sample
066         * @param proportion
067         *            the proportion of rows from the original to include in the
068         *            sample
069         * @throws IllegalArgumentException
070         *             if the proportion is less than 0 or bigger than 1.
071         */
072        public RandomSampleDataSource(DataSource<DATATYPE> dataSource, double proportion) {
073                super(dataSource, RandomData.getUniqueRandomInts(
074                                (int) (proportion * dataSource.size()),
075                                0,
076                                dataSource.size()));
077        }
078}