/**
* 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.impl.model;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import com.google.common.collect.Lists;
import org.apache.mahout.cf.taste.common.NoSuchItemException;
import org.apache.mahout.cf.taste.common.NoSuchUserException;
import org.apache.mahout.cf.taste.common.Refreshable;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastByIDMap;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveArrayIterator;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.Preference;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Preconditions;
/**
* <p>
* A simple {@link DataModel} which uses a given {@link List} of users as its data source. This implementation
* is mostly useful for small experiments and is not recommended for contexts where performance is important.
* </p>
*/
public final class GenericDataModel extends AbstractDataModel {
private static final Logger log = LoggerFactory.getLogger(GenericDataModel.class);
private final long[] userIDs;
private final FastByIDMap<PreferenceArray> preferenceFromUsers;
private final long[] itemIDs;
private final FastByIDMap<PreferenceArray> preferenceForItems;
private final FastByIDMap<FastByIDMap<Long>> timestamps;
/**
* <p>
* Creates a new from the given users (and their preferences). This
* {@link DataModel} retains all this information in memory and is effectively immutable.
* </p>
*
* @param userData users to include; (see also {@link #toDataMap(FastByIDMap, boolean)})
*/
public GenericDataModel(FastByIDMap<PreferenceArray> userData) {
this(userData, null);
}
/**
* <p>
* Creates a new from the given users (and their preferences). This
* {@link DataModel} retains all this information in memory and is effectively immutable.
* </p>
*
* @param userData users to include; (see also {@link #toDataMap(FastByIDMap, boolean)})
* @param timestamps optionally, provided timestamps of preferences as milliseconds since the epoch.
* User IDs are mapped to maps of item IDs to Long timestamps.
*/
public GenericDataModel(FastByIDMap<PreferenceArray> userData, FastByIDMap<FastByIDMap<Long>> timestamps) {
Preconditions.checkArgument(userData != null, "userData is null");
this.preferenceFromUsers = userData;
FastByIDMap<Collection<Preference>> prefsForItems = new FastByIDMap<Collection<Preference>>();
FastIDSet itemIDSet = new FastIDSet();
int currentCount = 0;
float maxPrefValue = Float.NEGATIVE_INFINITY;
float minPrefValue = Float.POSITIVE_INFINITY;
for (Map.Entry<Long, PreferenceArray> entry : preferenceFromUsers.entrySet()) {
PreferenceArray prefs = entry.getValue();
prefs.sortByItem();
for (Preference preference : prefs) {
long itemID = preference.getItemID();
itemIDSet.add(itemID);
Collection<Preference> prefsForItem = prefsForItems.get(itemID);
if (prefsForItem == null) {
prefsForItem = Lists.newArrayListWithCapacity(2);
prefsForItems.put(itemID, prefsForItem);
}
prefsForItem.add(preference);
float value = preference.getValue();
if (value > maxPrefValue) {
maxPrefValue = value;
}
if (value < minPrefValue) {
minPrefValue = value;
}
}
if (++currentCount % 10000 == 0) {
log.info("Processed {} users", currentCount);
}
}
log.info("Processed {} users", currentCount);
setMinPreference(minPrefValue);
setMaxPreference(maxPrefValue);
this.itemIDs = itemIDSet.toArray();
itemIDSet = null; // Might help GC -- this is big
Arrays.sort(itemIDs);
this.preferenceForItems = toDataMap(prefsForItems, false);
for (Map.Entry<Long, PreferenceArray> entry : preferenceForItems.entrySet()) {
entry.getValue().sortByUser();
}
this.userIDs = new long[userData.size()];
int i = 0;
LongPrimitiveIterator it = userData.keySetIterator();
while (it.hasNext()) {
userIDs[i++] = it.next();
}
Arrays.sort(userIDs);
this.timestamps = timestamps;
}
/**
* <p>
* Creates a new containing an immutable copy of the data from another given
* {@link DataModel}.
* </p>
*
* @param dataModel {@link DataModel} to copy
* @throws TasteException if an error occurs while retrieving the other {@link DataModel}'s users
* @deprecated without direct replacement.
* Consider {@link #toDataMap(DataModel)} with {@link #GenericDataModel(FastByIDMap)}
*/
@Deprecated
public GenericDataModel(DataModel dataModel) throws TasteException {
this(toDataMap(dataModel));
}
/**
* Swaps, in-place, {@link List}s for arrays in {@link Map} values .
*
* @return input value
*/
public static FastByIDMap<PreferenceArray> toDataMap(FastByIDMap<Collection<Preference>> data,
boolean byUser) {
for (Map.Entry<Long,Object> entry : ((FastByIDMap<Object>) (FastByIDMap<?>) data).entrySet()) {
List<Preference> prefList = (List<Preference>) entry.getValue();
entry.setValue(byUser ? new GenericUserPreferenceArray(prefList) : new GenericItemPreferenceArray(
prefList));
}
return (FastByIDMap<PreferenceArray>) (FastByIDMap<?>) data;
}
/**
* Exports the simple user IDs and preferences in the data model.
*
* @return a {@link FastByIDMap} mapping user IDs to {@link PreferenceArray}s representing
* that user's preferences
*/
public static FastByIDMap<PreferenceArray> toDataMap(DataModel dataModel) throws TasteException {
FastByIDMap<PreferenceArray> data = new FastByIDMap<PreferenceArray>(dataModel.getNumUsers());
LongPrimitiveIterator it = dataModel.getUserIDs();
while (it.hasNext()) {
long userID = it.nextLong();
data.put(userID, dataModel.getPreferencesFromUser(userID));
}
return data;
}
/**
* This is used mostly internally to the framework, and shouldn't be relied upon otherwise.
*/
public FastByIDMap<PreferenceArray> getRawUserData() {
return this.preferenceFromUsers;
}
/**
* This is used mostly internally to the framework, and shouldn't be relied upon otherwise.
*/
public FastByIDMap<PreferenceArray> getRawItemData() {
return this.preferenceForItems;
}
@Override
public LongPrimitiveArrayIterator getUserIDs() {
return new LongPrimitiveArrayIterator(userIDs);
}
/**
* @throws NoSuchUserException
* if there is no such user
*/
@Override
public PreferenceArray getPreferencesFromUser(long userID) throws NoSuchUserException {
PreferenceArray prefs = preferenceFromUsers.get(userID);
if (prefs == null) {
throw new NoSuchUserException(userID);
}
return prefs;
}
@Override
public FastIDSet getItemIDsFromUser(long userID) throws TasteException {
PreferenceArray prefs = getPreferencesFromUser(userID);
int size = prefs.length();
FastIDSet result = new FastIDSet(size);
for (int i = 0; i < size; i++) {
result.add(prefs.getItemID(i));
}
return result;
}
@Override
public LongPrimitiveArrayIterator getItemIDs() {
return new LongPrimitiveArrayIterator(itemIDs);
}
@Override
public PreferenceArray getPreferencesForItem(long itemID) throws NoSuchItemException {
PreferenceArray prefs = preferenceForItems.get(itemID);
if (prefs == null) {
throw new NoSuchItemException(itemID);
}
return prefs;
}
@Override
public Float getPreferenceValue(long userID, long itemID) throws TasteException {
PreferenceArray prefs = getPreferencesFromUser(userID);
int size = prefs.length();
for (int i = 0; i < size; i++) {
if (prefs.getItemID(i) == itemID) {
return prefs.getValue(i);
}
}
return null;
}
@Override
public Long getPreferenceTime(long userID, long itemID) throws TasteException {
if (timestamps == null) {
return null;
}
FastByIDMap<Long> itemTimestamps = timestamps.get(userID);
if (itemTimestamps == null) {
throw new NoSuchUserException(userID);
}
return itemTimestamps.get(itemID);
}
@Override
public int getNumItems() {
return itemIDs.length;
}
@Override
public int getNumUsers() {
return userIDs.length;
}
@Override
public int getNumUsersWithPreferenceFor(long itemID) {
PreferenceArray prefs1 = preferenceForItems.get(itemID);
return prefs1 == null ? 0 : prefs1.length();
}
@Override
public int getNumUsersWithPreferenceFor(long itemID1, long itemID2) {
PreferenceArray prefs1 = preferenceForItems.get(itemID1);
if (prefs1 == null) {
return 0;
}
PreferenceArray prefs2 = preferenceForItems.get(itemID2);
if (prefs2 == null) {
return 0;
}
int size1 = prefs1.length();
int size2 = prefs2.length();
int count = 0;
int i = 0;
int j = 0;
long userID1 = prefs1.getUserID(0);
long userID2 = prefs2.getUserID(0);
while (true) {
if (userID1 < userID2) {
if (++i == size1) {
break;
}
userID1 = prefs1.getUserID(i);
} else if (userID1 > userID2) {
if (++j == size2) {
break;
}
userID2 = prefs2.getUserID(j);
} else {
count++;
if (++i == size1 || ++j == size2) {
break;
}
userID1 = prefs1.getUserID(i);
userID2 = prefs2.getUserID(j);
}
}
return count;
}
@Override
public void removePreference(long userID, long itemID) {
throw new UnsupportedOperationException();
}
@Override
public void setPreference(long userID, long itemID, float value) {
throw new UnsupportedOperationException();
}
@Override
public void refresh(Collection<Refreshable> alreadyRefreshed) {
// Does nothing
}
@Override
public boolean hasPreferenceValues() {
return true;
}
@Override
public String toString() {
StringBuilder result = new StringBuilder(200);
result.append("GenericDataModel[users:");
for (int i = 0; i < Math.min(3, userIDs.length); i++) {
if (i > 0) {
result.append(',');
}
result.append(userIDs[i]);
}
if (userIDs.length > 3) {
result.append("...");
}
result.append(']');
return result.toString();
}
}