/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.cf.taste.example.kddcup.track1.svd;
import com.google.common.collect.Lists;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.impl.model.GenericPreference;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.Preference;
import java.util.List;
/**
* can be used to drop {@link DataModel}s into {@link ParallelArraysSGDFactorizer}
*/
public class DataModelFactorizablePreferences implements FactorizablePreferences {
private final FastIDSet userIDs;
private final FastIDSet itemIDs;
private final List<Preference> preferences;
private final float minPreference;
private final float maxPreference;
public DataModelFactorizablePreferences(DataModel dataModel) {
minPreference = dataModel.getMinPreference();
maxPreference = dataModel.getMaxPreference();
try {
userIDs = new FastIDSet(dataModel.getNumUsers());
itemIDs = new FastIDSet(dataModel.getNumItems());
preferences = Lists.newArrayList();
LongPrimitiveIterator userIDsIterator = dataModel.getUserIDs();
while (userIDsIterator.hasNext()) {
long userID = userIDsIterator.nextLong();
userIDs.add(userID);
for (Preference preference : dataModel.getPreferencesFromUser(userID)) {
itemIDs.add(preference.getItemID());
preferences.add(new GenericPreference(userID, preference.getItemID(), preference.getValue()));
}
}
} catch (TasteException te) {
throw new IllegalStateException("Unable to create factorizable preferences!", te);
}
}
@Override
public LongPrimitiveIterator getUserIDs() {
return userIDs.iterator();
}
@Override
public LongPrimitiveIterator getItemIDs() {
return itemIDs.iterator();
}
@Override
public Iterable<Preference> getPreferences() {
return preferences;
}
@Override
public float getMinPreference() {
return minPreference;
}
@Override
public float getMaxPreference() {
return maxPreference;
}
@Override
public int numUsers() {
return userIDs.size();
}
@Override
public int numItems() {
return itemIDs.size();
}
@Override
public int numPreferences() {
return preferences.size();
}
}