TriangularMatrix.java

package ca.pfv.spmf.datastructures.triangularmatrix;

import ca.pfv.spmf.algorithms.frequentpatterns.charm.AlgoCharm_Bitset;
import ca.pfv.spmf.algorithms.frequentpatterns.eclat.AlgoEclat;
import ca.pfv.spmf.algorithms.frequentpatterns.eclat.AlgoEclat_Bitset;

/* This file is copyright (c) 2008-2013 Philippe Fournier-Viger
* 
* This file is part of the SPMF DATA MINING SOFTWARE
* (http://www.philippe-fournier-viger.com/spmf).
* 
* SPMF 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.
* 
* SPMF 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
* SPMF. If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * This class is for creating a triangular matrix of integers represented by using arrays.
 * All the elements in the matrix are initialized to zero and can
 * be changed to other integer values.
 * For example: <br/><br/>
 * 
 * 0: [0, 0, 0, 0]<br/>
 * 1: [0, 0, 0]<br/>
 * 2: [0, 0]<br/>
 * 3: [0]
 * <br/><br/>
 * 
 * This structure is used by various data mining algorithms such as CHARM
 * and ECLAT.
 * 
 * @see AbstractTriangularMatrix
 * @see SparseTriangularMatrix
 * @see AlgoCharm_Bitset
 * @see AlgoEclat_Bitset
 * @see AlgoEclat
 * @author Philippe Fournier-Viger
 */
public class TriangularMatrix implements AbstractTriangularMatrix {
	
	// the triangular matrix is a two dimension array of integers
	private int[][] matrix;
	// the number of lines in the matrix
	private int elementCount;

	/**
	 * Constructor of a new triangular matrix.
	 * @param elementCount the desired number of lines in the matrix.
	 */
	public TriangularMatrix(int elementCount){
		// save the number of lines
		this.elementCount = elementCount;
		// initialize the matrix
		matrix = new int[elementCount-1][]; // -1 cause we want it shorter of 1 element
		for(int i=0; i< elementCount-1; i++){ // -1 cause we want it shorter of 1 element
		   // allocate an array for each row
			matrix[i] = new int[elementCount - i -1];
		}
	}
	
	/**
	 * Get the value at a given position in the matrix
	 * @param i  the row
	 * @param j  the column
	 * @return the value
	 */
	private int get(int i, int j){
		return matrix[i][j];
	}
	
	/**
	 * Main method for testing and debugging only!
	 */
	public static void main(String[] args) {
		TriangularMatrix a = new TriangularMatrix(5);

		System.out.println(a.toString());
		// AB, AD, AE, BD, BE, DE
		a.incrementCount(1, 0);
		System.out.println(a.toString());
		a.incrementCount(1, 4);
		a.incrementCount(1, 3);
		a.incrementCount(2, 4);
		a.incrementCount(2, 4);
		a.incrementCount(4, 3);
		System.out.println(a.toString());
		a.incrementCount(0, 2);
		a.incrementCount(0, 3);
		a.incrementCount(0, 4);
		System.out.println(a.toString());
	}
	
	/* (non-Javadoc)
	 * @see ca.pfv.spmf.datastructures.triangularmatrix.AbstractTriangularMatrix#toString()
	 */
	public String toString() {
		// print the number of elements
		System.out.println("Element count = " + elementCount);
		// create a string buffer
		StringBuilder temp = new StringBuilder();
		// for each row
		for (int i = 0; i < matrix.length; i++) {
			temp.append(i);
			temp.append(": ");
			// for each column
			for (int j = 0; j < matrix[i].length; j++) {
				temp.append(matrix[i][j]); // add the value at position i,j
				temp.append(" ");
			}
			temp.append("\n");
		}
		return temp.toString();
	}

	/* (non-Javadoc)
	 * @see ca.pfv.spmf.datastructures.triangularmatrix.AbstractTriangularMatrix#incrementCount(int, int)
	 */
	public void incrementCount(int i, int j) {
		if(j < i){
			matrix[elementCount - i -1][j]++;  // so that id is always smaller than j
		}else{
			matrix[elementCount - j -1][i]++;
		}
	}
	
	/* (non-Javadoc)
	 * @see ca.pfv.spmf.datastructures.triangularmatrix.AbstractTriangularMatrix#getSupportForItems(int, int)
	 */
	public int getSupportForItems(int i, int j){
		if(j < i){
			return matrix[elementCount - i -1][j];  // so that id is always smaller than id2
		}else{
			return matrix[elementCount - j -1][i];
		}
	}

	/* (non-Javadoc)
	 * @see ca.pfv.spmf.datastructures.triangularmatrix.AbstractTriangularMatrix#setSupport(java.lang.Integer, java.lang.Integer, int)
	 */
	public void setSupport(Integer i, Integer j, int support) {
		if(j < i){
			matrix[elementCount - i -1][j] = support;  // so that id is always smaller than j
		}else{
			matrix[elementCount - j -1][i] = support;
		}
	}
}