Repository /Debellor/debellor-1.0.jar:org.debellor.base.FlattenVectors

/*
 *  Debellor
 *
 *  Copyright (C) 2008-2009 by Marcin Wojnarski
 *
 *  This program 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.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package org.debellor.base;

import java.util.ArrayList;
import java.util.Arrays;

import org.debellor.core.Cell;
import org.debellor.core.DataObject;
import org.debellor.core.DataType;
import org.debellor.core.Sample;
import org.debellor.core.Sample.SampleType;
import org.debellor.core.data.DataVector;
import org.debellor.core.data.DataVector.DataVectorType;

/**
 * Flattens DataVectors whose items are other DataVectors.
 * The items are concatenated into a single DataVector.
 * This is done only for <code>data</code> field of samples,
 * decision is untouched.
 * 
 * @author Marcin Wojnarski
 *
 */
public class FlattenVectors extends Cell {

	/** Temporary variable used in onNext */
	private DataObject[] items;
	private Stream input;

	
	public FlattenVectors() {
		super(false);
	}

	@Override
	protected SampleType onOpen() throws Exception {
		input = openInputStream();
		SampleType inputType = input.sampleType;
		
		ArrayList<DataType> listOfItems = new ArrayList<DataType>();
		DataVectorType inputData = (DataVectorType) inputType.data;
		for(int i = 0; i < inputData.size(); i++) {
			// assumption: all items are DataVectors themselves
			DataVectorType item = (DataVectorType) inputData.get(i);
			listOfItems.addAll(Arrays.asList( item.get() ));
		}
		
		DataType[] itemTypes = new DataType[ listOfItems.size() ]; 
		listOfItems.toArray(itemTypes);
		
		DataVectorType dataType = new DataVectorType(itemTypes);
		SampleType type = new SampleType(dataType, inputType.decision);
		
		items = new DataObject[ itemTypes.length ];
		
		return type;
	}

	@Override
	protected Sample onNext() throws Exception {
		Sample s = input.next();
		if(s == null) return null;

		DataVector inputData = (DataVector) s.data;
		for(int i = 0, j = 0; i < inputData.size(); i++) {
			DataVector v = (DataVector) inputData.get(i);
			for(DataObject item : v.get())
				items[j++] = item;
		}

		DataVector data = new DataVector(items);
		return s.setData(data);
	}

	@Override
	protected void onClose() throws Exception {
		input.close();
		items = null;
	}

}