/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 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, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.knn.user;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import it.unimi.dsi.fastutil.longs.*;
import org.grouplens.grapht.annotation.DefaultProvider;
import org.grouplens.lenskit.collections.LongKeyDomain;
import org.grouplens.lenskit.collections.LongUtils;
import org.grouplens.lenskit.core.Shareable;
import org.grouplens.lenskit.core.Transient;
import org.grouplens.lenskit.cursors.Cursor;
import org.grouplens.lenskit.data.dao.UserEventDAO;
import org.grouplens.lenskit.data.event.Event;
import org.grouplens.lenskit.data.history.UserHistory;
import org.grouplens.lenskit.data.history.UserHistorySummarizer;
import org.grouplens.lenskit.transform.normalize.UserVectorNormalizer;
import org.grouplens.lenskit.vectors.ImmutableSparseVector;
import org.grouplens.lenskit.vectors.MutableSparseVector;
import javax.annotation.concurrent.ThreadSafe;
import javax.inject.Inject;
import javax.inject.Provider;
import java.io.Serializable;
import java.util.List;
/**
* User snapshot used by {@link SnapshotNeighborFinder}.
* @author <a href="http://www.grouplens.org">GroupLens Research</a>
* @since 2.1
*/
@Shareable
@ThreadSafe
@DefaultProvider(UserSnapshot.Builder.class)
public class UserSnapshot implements Serializable {
private static final long serialVersionUID = 1L;
private final LongKeyDomain users;
private final List<ImmutableSparseVector> vectors;
private final List<ImmutableSparseVector> normedVectors;
private final Long2ObjectMap<LongSortedSet> itemUserSets;
/**
* Construct a user snapshot.
* @param us The set of users.
* @param vs The list of raw user vectors.
* @param nvs The list of normalized user vectors.
*/
UserSnapshot(LongKeyDomain us, List<ImmutableSparseVector> vs, List<ImmutableSparseVector> nvs,
Long2ObjectMap<LongSortedSet> iuSets) {
Preconditions.checkArgument(vs.size() == us.domainSize(),
"incorrectly sized vector list");
Preconditions.checkArgument(nvs.size() == us.domainSize(),
"incorrectly sized normalized vector list");
users = us.clone();
vectors = ImmutableList.copyOf(vs);
normedVectors = ImmutableList.copyOf(nvs);
itemUserSets = iuSets;
}
public ImmutableSparseVector getUserVector(long user) {
int idx = users.getIndexIfActive(user);
Preconditions.checkArgument(idx >= 0, "invalid user " + user);
return vectors.get(idx);
}
public ImmutableSparseVector getNormalizedUserVector(long user) {
int idx = users.getIndexIfActive(user);
Preconditions.checkArgument(idx >= 0, "invalid user " + user);
return normedVectors.get(idx);
}
public LongSet getItemUsers(long item) {
return itemUserSets.get(item);
}
public static class Builder implements Provider<UserSnapshot> {
private final UserEventDAO userEventDAO;
private final UserVectorNormalizer normalizer;
private final UserHistorySummarizer summarizer;
@Inject
public Builder(@Transient UserEventDAO dao,
@Transient UserVectorNormalizer norm,
@Transient UserHistorySummarizer sum) {
userEventDAO = dao;
normalizer = norm;
summarizer = sum;
}
@Override
public UserSnapshot get() {
Long2ObjectMap<MutableSparseVector> vectors = new Long2ObjectOpenHashMap<MutableSparseVector>();
Cursor<? extends UserHistory<? extends Event>> users = userEventDAO.streamEventsByUser(summarizer.eventTypeWanted());
try {
for (UserHistory<? extends Event> user: users) {
MutableSparseVector uvec = summarizer.summarize(user).mutableCopy();
vectors.put(user.getUserId(), uvec);
}
} finally {
users.close();
}
Long2ObjectMap<LongList> itemUserLists = new Long2ObjectOpenHashMap<LongList>();
LongKeyDomain domain = LongKeyDomain.fromCollection(vectors.keySet()).compactCopy(true);
assert domain.size() == domain.domainSize();
ImmutableList.Builder<ImmutableSparseVector> vecs = ImmutableList.builder();
ImmutableList.Builder<ImmutableSparseVector> nvecs = ImmutableList.builder();
for (LongIterator uiter = domain.activeSetView().iterator(); uiter.hasNext();) {
final long user = uiter.nextLong();
MutableSparseVector vec = vectors.get(user);
// save user's original vector
ImmutableSparseVector userVector = vec.immutable();
vecs.add(userVector);
// normalize user vector
normalizer.normalize(user, userVector, vec);
// and save normalized vector
nvecs.add(vec.immutable());
for (LongIterator iiter = userVector.keySet().iterator(); iiter.hasNext();) {
final long item = iiter.nextLong();
LongList itemUsers = itemUserLists.get(item);
if (itemUsers == null) {
itemUsers = new LongArrayList();
itemUserLists.put(item, itemUsers);
}
itemUsers.add(user);
}
}
Long2ObjectMap<LongSortedSet> itemUserSets = new Long2ObjectOpenHashMap<LongSortedSet>();
for (Long2ObjectMap.Entry<LongList> entry: itemUserLists.long2ObjectEntrySet()) {
itemUserSets.put(entry.getLongKey(), LongUtils.packedSet(entry.getValue()));
}
return new UserSnapshot(domain.unowned(), vecs.build(), nvecs.build(), itemUserSets);
}
}
}