/*
* RapidMiner
*
* Copyright (C) 2001-2008 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.example.set;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
/**
* This example reader is based on the given mapping and skips all examples which are not
* part of the mapping. This implementation is quite inefficient on databases and other
* non-memory example tables and should therefore only be used for small data sets.
*
* @author Ingo Mierswa
* @version $Id: SortedExampleReader.java,v 1.5 2008/05/09 19:22:49 ingomierswa Exp $
*/
public class SortedExampleReader extends AbstractExampleReader {
/** The parent example set. */
private ExampleSet parent;
/** The current index in the mapping. */
private int currentIndex;
/** Indicates if the current example was "delivered" by a call of {@link #next()}. */
private boolean nextInvoked = true;
/** The example that will be returned by the next invocation of next(). */
private Example currentExample = null;
/** Constructs a new mapped example reader. */
public SortedExampleReader(ExampleSet parent) {
this.parent = parent;
this.currentIndex = 0;
}
public boolean hasNext() {
if (this.nextInvoked) {
this.nextInvoked = false;
if (this.currentIndex < parent.size()) {
this.currentExample = this.parent.getExample(this.currentIndex);
this.currentIndex++;
} else {
return false;
}
}
return true;
}
public Example next() {
if (hasNext()) {
this.nextInvoked = true;
return currentExample;
} else {
return null;
}
}
}