Sequence.java

/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.learner.associations.gsp;

import java.util.ArrayList;
import java.util.Iterator;


/**
 * @author Sebastian Land
 *
 */
public class Sequence extends ArrayList<Transaction> implements Comparable<Sequence>{

	private static final long serialVersionUID = -5774432548086375L;

	public Sequence() {};
	
	public Sequence(Sequence sequence) {
		addAll(sequence);
	}
	

	public int getNumberOfItems() {
		int size = 0;
		for (Transaction transaction: this) {
			size += transaction.size();
		}
		return size;
	}
	/**
	 * This method returns the n-th item in the sequence counting all items in every transaction
	 */
	public Item getItem(int n) {
		for (Transaction transaction: this) {
			if (n - transaction.size() < 0)
				return transaction.get(n);
			n -= transaction.size();
		}
		return null;
	}

	public Transaction getLastTransaction() {
		return get(size() - 1);
	}

	/** This method implements an enhanced equals method where the specified elements
	 * of the sequences are treated as if not existent. This avoids construction of
	 * new sequences.
	 */
	public boolean equals(int ignoreOwnElement, Sequence sequence, int ignoreItsElement) {
		int ownIndex = 0;
		int itsIndex = 0;
		Iterator<Item> ownIterator = itemIterator();
		Iterator<Item> itsIterator = sequence.itemIterator();
		while (true) {
			// shift both iterators to next items
			if (ignoreOwnElement == ownIndex) {
				ownIterator.next();
				ownIndex++;
			}
			if (ignoreItsElement == itsIndex) {
				itsIterator.next();
				itsIndex++;
			}
			
			// testing if abort
			if (!ownIterator.hasNext() || !itsIterator.hasNext()) {
				if (!ownIterator.hasNext() && !itsIterator.hasNext())
					return true;
				return false;
			}
		
			Item ownItem = ownIterator.next();
			Item itsItem = itsIterator.next();
			ownIndex++;
			itsIndex++;
			if (!ownItem.equals(itsItem))
				return false;
		}
	}

	public Iterator<Item> itemIterator () {
		return new Iterator<Item>() {
			private Iterator<Transaction> transactionIterator = iterator();
			private Iterator<Item> itemIterator;
			
			@Override
			public boolean hasNext() {
				if (transactionIterator.hasNext())
					return true;
				if (itemIterator != null)
					if (itemIterator.hasNext())
						return true;
				return false;
			}

			@Override
			public Item next() {
				if (itemIterator == null)
					itemIterator = transactionIterator.next().iterator();
				if (!itemIterator.hasNext())
					itemIterator = transactionIterator.next().iterator();
				return itemIterator.next();
			}

			@Override
			public void remove() {
				// not supported
			}
		};
	}
	
	/**
	 * This method returns a Sequence, with the specified transaction appended.
	 * It has to take care, that neither the original sequence nor the original transaction is altered.
	 */
	public static Sequence appendTransaction(Sequence sequence1, Transaction lastTransaction) {
		Sequence result = new Sequence(sequence1);
		result.add(lastTransaction);
		return result;
	}

	/**
	 * This method returns a Sequence, with the specified item appended on the last transaction.
	 * It has to take care, that neither the original sequence nor the original transaction is altered.
	 */
	public static Sequence appendItem(Sequence sequence1, Item lastItem) {
		Sequence result = new Sequence(sequence1);
		int lastIndex = result.size() - 1;
		Transaction newTransaction = new Transaction(result.get(lastIndex));
		
		result.remove(lastIndex);
		newTransaction.add(lastItem);
		
		result.add(newTransaction);
		return result;
	}

	public static Sequence removeItem(Sequence candidate, int transactionIndex, int itemIndex) {
		Sequence result = new Sequence(candidate);
		Transaction newTransaction = new Transaction(result.get(transactionIndex));
		newTransaction.remove(itemIndex);
		if (newTransaction.size() > 0)
			result.set(transactionIndex, newTransaction);
		else
			result.remove(transactionIndex);
		return result;
	}





	
	@Override
	public String toString() {
		StringBuffer buffer = new StringBuffer();
		for (Transaction transaction: this) {
			buffer.append("<" + transaction.toString() + ">  ");
		}
		return buffer.toString();
	}

	@Override
	public int compareTo(Sequence o) {
		int itsSize = o.getNumberOfItems();
		int mySize = getNumberOfItems();
		if (itsSize == mySize) {
			Iterator<Item> myItem = itemIterator();
			Iterator<Item> itsItem = o.itemIterator();
			while (myItem.hasNext() && itsItem.hasNext()) {
				int itsIndex = itsItem.next().getIndex();
				int myIndex = myItem.next().getIndex();
				if (itsIndex != myIndex)
					return (myIndex > itsIndex)? 1 : -1;
			}
			return 0;
		}else {
			return (mySize > itsSize)? 1: -1;
		}
	}
}