// Copyright (C) 2010, 2011 Zeno Gantner, Chris Newell
//
// This file is part of MyMediaLite.
//
// MyMediaLite 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.
//
// MyMediaLite 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 MyMediaLite. If not, see <http://www.gnu.org/licenses/>.
package org.mymedialite.ratingprediction;
import java.util.List;
import org.mymedialite.IItemAttributeAwareRecommender;
import org.mymedialite.correlation.BinaryCosine;
import org.mymedialite.datatype.SparseBooleanMatrix;
import org.mymedialite.util.Memoizer;
/**
* Attribute-aware weighted item-based kNN recommender.
*
* This recommender does NOT support incremental updates.
* @version 2.03
*/
public class ItemAttributeKNN extends ItemKNN implements IItemAttributeAwareRecommender {
private SparseBooleanMatrix itemAttributes;
private int numItemAttributes;
public SparseBooleanMatrix getItemAttributes() {
return itemAttributes;
}
public void setItemAttributes(SparseBooleanMatrix matrix) {
this.itemAttributes = matrix;
this.numItemAttributes = itemAttributes.numberOfColumns();
this.maxItemID = Math.max(maxItemID, itemAttributes.numberOfRows() - 1);
}
/**
*
*/
protected void retrainItem(int item_id) {
baseline_predictor.retrainItem(item_id);
}
/**
*
*/
public int numItemAttributes() {
return numItemAttributes;
}
/**
*
*/
public void train() {
baseline_predictor.train();
this.correlation = BinaryCosine.create(itemAttributes);
memoizer = new Memoizer<Integer, List<Integer>>(correlation, "getPositivelyCorrelatedEntities", Integer.TYPE);
}
/**
*/
public String toString() {
return "ItemAttributeKNN k=" + (k == Integer.MAX_VALUE ? "inf" : k) + " reg_u=" + getRegU() + " reg_i=" + getRegI();
}
}