TransactionDatabase.java

package ca.pfv.spmf.input.transaction_database_list_integers;
/* 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/>.
*/
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * This class represents a transaction database (a.k.a. binary context), implemented
 * as a list of integers. It can read a transaction database directly from a file. 
 * See the ca.pfv.spmf.test folder for some examples of files that can be 
 * read.
 * @author Philipe-Fournier-Viger
 */
public class TransactionDatabase {

	// The list of items in this database
	private final Set<Integer> items = new HashSet<Integer>();
	// the list of transactions
	private final List<List<Integer>> transactions = new ArrayList<List<Integer>>();

	/**
	 * Method to add a new transaction to this database.
	 * @param transaction  the transaction to be added
	 */
	public void addTransaction(List<Integer> transaction) {
		transactions.add(transaction);
		items.addAll(transaction);
	}

	/**
	 * Method to load a file containing a transaction database into memory
	 * @param path the path of the file
	 * @throws IOException exception if error reading the file
	 */
	public void loadFile(String path) throws IOException {
		String thisLine; // variable to read each line
		BufferedReader myInput = null; // object to read the file
		try {
			FileInputStream fin = new FileInputStream(new File(path));
			myInput = new BufferedReader(new InputStreamReader(fin));
			// for each line
			while ((thisLine = myInput.readLine()) != null) {
				// if the line is not a comment, is not empty or is not other
				// kind of metadata
				if (thisLine.isEmpty() == false &&
						thisLine.charAt(0) != '#' && thisLine.charAt(0) != '%'
						&& thisLine.charAt(0) != '@') {
					// split the line according to spaces and then
					// call "addTransaction" to process this line.
					addTransaction(thisLine.split(" "));
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (myInput != null) {
				myInput.close();
			}
		}
	}

	/**
	 * This method process a line from a file that is read.
	 * @param tokens the items contained in this line
	 */
	private void addTransaction(String itemsString[]) {
		// create an empty transaction
		List<Integer> itemset = new ArrayList<Integer>();
		// for each item in this line
		for (String attribute : itemsString) {
			// convert from string to int
			int item = Integer.parseInt(attribute);
			// add the item to the current transaction
			itemset.add(item); 
			// add the item to the set of all items in this database
			items.add(item);
		}
		// add the transactions to the list of all transactions in this database.
		transactions.add(itemset);
	}

	/**
	 * Method to print the content of the transaction database to the console.
	 */
	public void printDatabase() {
		System.out
				.println("===================  TRANSACTION DATABASE ===================");
		int count = 0; 
		// for each transaction
		for (List<Integer> itemset : transactions) { // pour chaque objet
			System.out.print("0" + count + ":  ");
			print(itemset); // print the transaction 
			System.out.println("");
			count++;
		}
	}
	
	/**
	 * Method to print a transaction to System.out.
	 * @param itemset a transaction
	 */
	private void print(List<Integer> itemset){
		StringBuilder r = new StringBuilder();
		// for each item in this transaction
		for (Integer item : itemset) {
			// append the item to the StringBuilder
			r.append(item.toString());
			r.append(' ');
		}
		System.out.println(r); // print to System.out
	}

	/**
	 * Get the number of transactions in this transaction database.
	 * @return the number of transactions.
	 */
	public int size() {
		return transactions.size();
	}

	/**
	 * Get the list of transactions in this database
	 * @return A list of transactions (a transaction is a list of Integer).
	 */
	public List<List<Integer>> getTransactions() {
		return transactions;
	}

	/**
	 * Get the set of items contained in this database.
	 * @return The set of items.
	 */
	public Set<Integer> getItems() {
		return items;
	}
}