001    /*
002     * Copyright (C) 2008-2010 by Holger Arndt
003     *
004     * This file is part of the Universal Java Matrix Package (UJMP).
005     * See the NOTICE file distributed with this work for additional
006     * information regarding copyright ownership and licensing.
007     *
008     * UJMP is free software; you can redistribute it and/or modify
009     * it under the terms of the GNU Lesser General Public License as
010     * published by the Free Software Foundation; either version 2
011     * of the License, or (at your option) any later version.
012     *
013     * UJMP is distributed in the hope that it will be useful,
014     * but WITHOUT ANY WARRANTY; without even the implied warranty of
015     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
016     * GNU Lesser General Public License for more details.
017     *
018     * You should have received a copy of the GNU Lesser General Public
019     * License along with UJMP; if not, write to the
020     * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
021     * Boston, MA  02110-1301  USA
022     */
023    
024    package org.ujmp.core.objectmatrix.calculation;
025    
026    import java.util.ArrayList;
027    import java.util.List;
028    
029    import org.ujmp.core.Matrix;
030    import org.ujmp.core.exceptions.MatrixException;
031    import org.ujmp.core.util.MathUtil;
032    
033    public class Bootstrap extends AbstractObjectCalculation {
034            private static final long serialVersionUID = -5084329826465538416L;
035    
036            private int count = 0;
037    
038            private Matrix selection = null;
039    
040            public Bootstrap(Matrix m) {
041                    this(m, (int) m.getRowCount());
042            }
043    
044            public Bootstrap(Matrix m, int count) {
045                    super(m);
046                    this.count = count;
047            }
048    
049            public Object getObject(long... coordinates) throws MatrixException {
050                    if (selection == null) {
051                            List<Integer> rows = new ArrayList<Integer>();
052                            for (int i = 0; i < count; i++) {
053                                    int s = MathUtil.nextInteger(0, (int) getSource().getRowCount() - 1);
054                                    rows.add(s);
055                            }
056                            selection = getSource().selectRows(Ret.LINK, rows);
057                    }
058                    return selection.getAsObject(coordinates);
059            }
060    
061            @Override
062            public long[] getSize() {
063                    return new long[] { count, getSource().getColumnCount() };
064            }
065    
066    }