/* * RapidMiner * * Copyright (C) 2001-2014 by RapidMiner and the contributors * * Complete list of developers available at our web site: * * http://rapidminer.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; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; /** * The power set of a collection of items. * * @author Sebastian Land * * @param <ItemT> the item type */ public class PowerSet<ItemT> implements Iterable<Collection<ItemT>>, Iterator<Collection<ItemT>>{ private ArrayList<ItemT> set; private boolean[] subSetIndicator; public PowerSet(Collection<ItemT> collection) { set = new ArrayList<ItemT>(collection); } public Iterator<Collection<ItemT>> iterator() { return new PowerSet<ItemT>(set); } public Collection<ItemT> getComplement(Collection<ItemT> collection) { Collection<ItemT> complement = new ArrayList<ItemT>(set.size() - collection.size()); Iterator<ItemT> iterator = set.iterator(); for (ItemT item: collection) { while(iterator.hasNext()) { ItemT currentSetItem = iterator.next(); if (currentSetItem == item) { break; } else { complement.add(currentSetItem); } } } while(iterator.hasNext()) { complement.add(iterator.next()); } return complement; } public boolean hasNext() { if (subSetIndicator == null) { return true; } else { for (int i = 0; i < subSetIndicator.length; i++) { if (!subSetIndicator[i]) { return true; } } return false; } } public Collection<ItemT> next() { // do initialising if (subSetIndicator == null) { subSetIndicator = new boolean[set.size()]; } else { // increase binary counter for (int i = 0; i < subSetIndicator.length; i++) { if (subSetIndicator[i]) { // flipping 1 from right to left subSetIndicator[i] = false; } else { // found zero: flip to 1 subSetIndicator[i] = true; break; } } } // generating subset ArrayList<ItemT> subset = new ArrayList<ItemT>(); for (int i = 0; i < subSetIndicator.length; i++) { if (subSetIndicator[i]) { subset.add(set.get(i)); } } return subset; } /** Throws an {@link UnsupportedOperationException} since removal is not supported. */ public void remove() { throw new UnsupportedOperationException("The 'remove' operation is not supported by power sets!"); } }