i5.las2peer.services.recommender.librec.data.DiagMatrix.java Source code

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Here is the source code for i5.las2peer.services.recommender.librec.data.DiagMatrix.java

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// Copyright (C) 2014 Guibing Guo
//
// This file is part of LibRec.
//
// LibRec is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// LibRec is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with LibRec. If not, see <http://www.gnu.org/licenses/>.
//

package i5.las2peer.services.recommender.librec.data;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.Table;

/**
 * Data Structure: Diagonal Matrix
 * 
 * @author guoguibing
 * 
 */
public class DiagMatrix extends SparseMatrix {

    private static final long serialVersionUID = -9186836460633909994L;

    public DiagMatrix(int rows, int cols, Table<Integer, Integer, Double> dataTable,
            Multimap<Integer, Integer> colMap) {
        super(rows, cols, dataTable, colMap);
    }

    public DiagMatrix(DiagMatrix mat) {
        super(mat);
    }

    public DiagMatrix clone() {
        return new DiagMatrix(this);
    }

    public DiagMatrix scale(double val) {

        DiagMatrix res = this.clone();
        for (int i = 0; i < res.numRows; i++)
            res.set(i, i, this.get(i, i) * val);

        return res;
    }

    public DiagMatrix add(DiagMatrix that) {

        DiagMatrix res = this.clone();
        for (int i = 0; i < res.numRows; i++)
            res.set(i, i, this.get(i, i) + that.get(i, i));

        return res;
    }

    /**
     * Each diagonal entry addes {@code val}
     * 
     * @param val
     *            a value to be added
     * @return a new diagonal matrix
     */
    public DiagMatrix add(double val) {

        DiagMatrix res = this.clone();
        for (int i = 0; i < res.numRows; i++)
            res.set(i, i, this.get(i, i) + val);

        return res;
    }

    public DiagMatrix minus(DiagMatrix that) {

        DiagMatrix res = this.clone();
        for (int i = 0; i < res.numRows; i++)
            res.set(i, i, this.get(i, i) - that.get(i, i));

        return res;
    }

    /**
     * Each diagonal entry abstracts {@code val}
     * 
     * @param val
     *            a value to be abstracted
     * @return a new diagonal matrix
     */
    public DiagMatrix minus(double val) {

        DiagMatrix res = this.clone();
        for (int i = 0; i < res.numRows; i++)
            res.set(i, i, this.get(i, i) - val);

        return res;
    }

    public static DiagMatrix eye(int n) {
        Table<Integer, Integer, Double> vals = HashBasedTable.create();
        Multimap<Integer, Integer> colMap = HashMultimap.create();
        for (int i = 0; i < n; i++) {
            vals.put(i, i, 1.0);
            colMap.put(i, i);
        }

        return new DiagMatrix(n, n, vals, colMap);
    }
}