Package edu.ucla.sspace.matrix

Source Code of edu.ucla.sspace.matrix.CellMaskedSparseMatrix

/*
* Copyright 2010 Keith Stevens
*
* This file is part of the S-Space package and is covered under the terms and
* conditions therein.
*
* The S-Space package is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation and distributed hereunder to you.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND NO REPRESENTATIONS OR WARRANTIES,
* EXPRESS OR IMPLIED ARE MADE.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, WE MAKE
* NO REPRESENTATIONS OR WARRANTIES OF MERCHANT- ABILITY OR FITNESS FOR ANY
* PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE OR DOCUMENTATION
* WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
* RIGHTS.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

package edu.ucla.sspace.matrix;

import edu.ucla.sspace.vector.SparseDoubleVector;
import edu.ucla.sspace.vector.MaskedSparseDoubleVectorView;

import java.util.HashMap;
import java.util.Map;


/**
* This {@link SparseMatrix} decorator allows every row and column index to be
* remapped to new indices.  The size of this matrix will depend on the number
* of mapped rows and columns.  Write-through access is allowed for each cell in
* the underlying matrix through the {@code set} method.  Array based accessors
* and getters are disabled when using this decorator.
*
* @author Keith Stevens
*/
public class CellMaskedSparseMatrix extends CellMaskedMatrix
        implements SparseMatrix, java.io.Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * The original underlying matrix.
     */
    private final SparseMatrix matrix;

    /**
     * An internal mapping from known row indices in this {@link
     * CellMaskedSparseMatrix} to rows in the backing {@link SparseMatrix}.
     */
    private final int[] rowMaskMap;

    /**
     * An internal mapping from row indices in the backing {@link SparseMatrix}
     * to known rows in this {@link CellMaskedSparseMatrix}.
     */
    private final Map<Integer, Integer> reverseRowMaskMap;

    /**
     * An internal mapping from known column indices in this {@link
     * CellMaskedSparseMatrix} to columns in the backing {@link SparseMatrix}.
     */
    private final int[] colMaskMap;

    /**
     * An internal mapping from column indices in the backing {@link
     * SparseMatrix} to known columns in this {@link CellMaskedSparseMatrix}.
     */
    private final Map<Integer, Integer> reverseColMaskMap;

    /**
     * Creates a new {@link CellMaskedSparseMatrix} from a given {@link
     * SparseMatrix} and maps, one for the row indices and one for the column
     * indices.  Only valid mappings should be included.
     *
     * @param matrix The underlying matrix to decorate
     * @param rowMaskMap A mapping from new indices to old indices in the
     *        original map for rows.
     * @param colMaskMap A mapping from new indices to old indices in the
     *        original map for columns.
     */
    public CellMaskedSparseMatrix(SparseMatrix matrix,
                                  int[] rowMaskMap,
                                  int[] colMaskMap) {
        super(matrix, rowMaskMap, colMaskMap);
        this.matrix = matrix;
        this.rowMaskMap = rowMaskMap;
        this.colMaskMap = colMaskMap;
        reverseRowMaskMap = new HashMap<Integer, Integer>();
        for (int i = 0; i < rowMaskMap.length; ++i)
            reverseRowMaskMap.put(rowMaskMap[i], i);
        reverseColMaskMap = new HashMap<Integer, Integer>();
        for (int i = 0; i < colMaskMap.length; ++i)
            reverseColMaskMap.put(colMaskMap[i], i);
    }

    /**
     * {@inheritDoc}
     */
    public SparseDoubleVector getRowVector(int row) {
        row = getIndexFromMap(rowMaskMap, row);
        return new MaskedSparseDoubleVectorView(
                matrix.getRowVector(row), colMaskMap, reverseColMaskMap);
    }

    /**
     * {@inheritDoc}
     */
    public SparseDoubleVector getColumnVector(int col) {
        col = getIndexFromMap(colMaskMap, col);
        return new MaskedSparseDoubleVectorView(
                matrix.getColumnVector(col), rowMaskMap, reverseRowMaskMap);
    }
}
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