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la4j - Linear Algebra for Java

Elegant and pure Java matrix library
/*
 * Copyright 2011, Vladimir Kostyukov
 * 
 * This file is part of la4j project (http://la4j.googlecode.com)
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 *      
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package la4j.matrix.dense;

import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import la4j.factory.DenseFactory;
import la4j.factory.Factory;
import la4j.matrix.AbstractMatrix;
import la4j.matrix.Matrix;
import la4j.vector.Vector;

public class DenseMatrix extends AbstractMatrix implements Matrix {

	private static final long serialVersionUID = 1L;

	private double self[][];

	public DenseMatrix() {
		this(0, 0);
	}

	public DenseMatrix(double array[][]) {
		super(new DenseFactory());
		
		this.self = array;
		this.rows = array.length;
		this.columns = array[0].length;
	}

	public DenseMatrix(int rows, int columns) {
		super(new DenseFactory());
		
		this.self = new double[rows][columns];
		this.rows = rows;
		this.columns = columns;
	}


	@Override
	public double get(int i, int j) {
		
		if (i >= rows || i < 0 || j >= columns || j < 0) throw new IndexOutOfBoundsException();
		
		return self[i][j];
	}

	@Override
	public void set(int i, int j, double value) {
		
		if (i >= rows || i < 0 || j >= columns || j < 0) throw new IndexOutOfBoundsException();
		
		self[i][j] = value;
	}
	

	@Override
	public void resize(int rows, int columns) {
		
		if (rows < 0 || columns < 0) throw new IllegalArgumentException();
		
		if (this.rows == rows && this.columns == columns) return;
		
		if (this.rows >= rows && this.columns >= columns) {

			this.rows = rows;
			this.columns = columns;
			
			return;
		
		}

		double newSelf[][] = new double[rows][columns];

		for (int i = 0; i < this.rows; i++) {
			System.arraycopy(self[i], 0, newSelf[i], 0, this.columns);
		}
		
		this.rows = rows;
		this.columns = columns;
		
		self = newSelf;
	}

	@Override
	public double[][] toArray() {
		return self;
	}

	@Override
	public double[][] toArrayCopy() {
		
		double copy[][] = new double[rows][columns];

		for (int i = 0; i < rows; i++) {
			System.arraycopy(self[i], 0, copy[i], 0, columns);
		}

		return copy;
	}

	@Override
	public void swapRows(int i, int j) {
		
		if (i >= rows || i < 0 || j >= rows || j < 0) throw new IndexOutOfBoundsException();
		
		if (i == j) return;
		
		double dd[] = self[i];
		self[i] = self[j];
		self[j] = dd;
	}

	@Override
	public void swapColumns(int i, int j) {

		if (i >= columns || i < 0 || j >= columns || j < 0) throw new IndexOutOfBoundsException();
		
		if (i == j) return;
		
		for (int ii = 0; ii < rows; ii++) {
			double d = self[ii][i];
			self[ii][i] = self[ii][j];
			self[ii][j] = d;
		}
	}
	
	@Override
	public int nonzero() {
		
		int result = 0;
		for (int i = 0; i < rows; i++) {
			for (int j = 0; j < columns; j++) {
				if (Math.abs(self[i][j]) > EPS) {
					result++;
				}
			}
		}
		
		return result;
	}

	@Override
	public Matrix transpose(Factory factory) {
		
		if (factory == null) throw new NullPointerException();
		
		double result[][] = new double[columns][rows];
		
		for (int i = 0; i < rows; i++) {
			for (int j = 0; j < columns; j++) {
				result[j][i] = self[i][j];
			}
		}

		return factory.createMatrix(result);
	}
	
	@Override
	public Vector getRow(int i) {
		
		if (i >= rows || i < 0) throw new IndexOutOfBoundsException();
		
		double result[] = new double[columns];
		
		for (int j = 0; j < columns; j++) {
			result[j] = self[i][j];
		}

		return factory.createVector(result);
	}

	@Override
	public Vector getColumn(int i) {
		
		if (i >= columns || i < 0) throw new IndexOutOfBoundsException();

		double result[] = new double[rows];
		
		for (int j = 0; j < rows; j++) {
			result[j] = self[j][i];
		}

		return factory.createVector(result);
	}

	@Override
	public void setColumn(int i, Vector column) {
		
		if (i >= columns || i < 0) throw new IndexOutOfBoundsException();
		
		if (rows != column.length()) throw new IllegalArgumentException();
		
		for (int j = 0; j < column.length(); j++) {
			self[j][i] = column.get(j);
		}
	}

	@Override
	public void setRow(int i, Vector row) {
		
		if (i >= rows || i < 0) throw new IndexOutOfBoundsException();
		
		if (columns != row.length()) throw new IllegalArgumentException();
		
		for (int j = 0; j < row.length(); j++) {
			self[i][j] = row.get(j);
		}
	}

	@Override
	public void writeExternal(ObjectOutput out) throws IOException {
	
		out.writeInt(rows);
		out.writeInt(columns);
		out.writeByte(META_MARKER);

		for (int i = 0; i < rows; i++) {
			for (int j = 0; j < columns; j++) {
				out.writeDouble(self[i][j]);
				out.writeByte(ELEMENT_MARKER);
			}
		}
	}

	@Override
	public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
		
		rows = in.readInt();
		columns = in.readInt();
		in.readByte();

		self = new double[rows][columns];

		for (int i = 0; i < rows; i++) {
			for (int j = 0; j < columns; j++) {
				self[i][j] = in.readDouble();
				in.readByte();
			}
		}
	}
	
	@Override
	public Matrix clone() {

		DenseMatrix dolly = (DenseMatrix) super.clone();
		
		dolly.self = self.clone();
		for (int i = 0; i < rows; i++) {
			dolly.self[i] = self[i].clone();
		}
		
		return dolly;
	}
}

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Vladimir Kostyukov
Software Developer Intel
Russian Federation Russian Federation
I've received a Master's Degree in Computer Science at the IT Faculty of Altai State Technical University, Russia.
 
Currently, I am Software Engineer at Intel Corporation.
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Web01 | 2.8.140709.1 | Last Updated 14 Nov 2011
Article Copyright 2011 by Vladimir Kostyukov
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