/*
* Copyright (C) 2015 RankSys http://ranksys.org
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package org.ranksys.compression.preferences;
import es.uam.eps.ir.ranksys.core.preference.IdPref;
import es.uam.eps.ir.ranksys.fast.index.FastItemIndex;
import es.uam.eps.ir.ranksys.fast.index.FastUserIndex;
import es.uam.eps.ir.ranksys.fast.preference.FastPreferenceData;
import es.uam.eps.ir.ranksys.fast.preference.IdxPref;
import es.uam.eps.ir.ranksys.fast.preference.TransposedPreferenceData;
import it.unimi.dsi.fastutil.doubles.DoubleIterator;
import it.unimi.dsi.fastutil.doubles.DoubleIterators;
import org.ranksys.compression.codecs.CODEC;
import org.ranksys.core.util.iterators.ArrayDoubleIterator;
import org.ranksys.core.util.tuples.Tuple2io;
import java.io.Serializable;
import java.util.function.Function;
import java.util.stream.Stream;
import static org.ranksys.compression.util.Delta.delta;
import static org.ranksys.core.util.tuples.Tuples.tuple;
/**
* PreferenceData for rating data using compression.
* <br>
* If you use this code, please cite the following papers:
* <ul>
* <li>Vargas, S., Macdonald, C., Ounis, I. (2015). Analysing Compression Techniques for In-Memory Collaborative Filtering. In Poster Proceedings of the 9th ACM Conference on Recommender Systems. <a href="http://ceur-ws.org/Vol-1441/recsys2015_poster2.pdf">http://ceur-ws.org/Vol-1441/recsys2015_poster2.pdf</a>.</li>
* <li>Catena, M., Macdonald, C., Ounis, I. (2014). On Inverted Index Compression for Search Engine Efficiency. In ECIR (pp. 359–371). doi:10.1007/978-3-319-06028-6_30</li>
* </ul>
* The code that reproduces the results of the RecSys 2015 poster by Vargas et al. in a separated project: <a href="http://github.com/saulvargas/recsys2015">http://github.com/saulvargas/recsys2015</a>
* <br>
* The search index compression technologies of the ECIR paper by Catena et al. is part of the Terrier IR Platform: <a href="http://terrier.org/docs/v4.0/compression.html">http://terrier.org/docs/v4.0/compression.html</a>.
*
* @param <U> type of users
* @param <I> type of items
* @param <Cu> coding for user identifiers
* @param <Ci> coding for item identifiers
* @param <Cv> coding for ratings
* @author Saúl Vargas (Saul.Vargas@glasgow.ac.uk)
*/
public class RatingCODECPreferenceData<U, I, Cu, Ci, Cv> extends AbstractCODECPreferenceData<U, I, Cu, Ci> {
/**
* CODEC for ratings.
*/
protected final CODEC<Cv> r_codec;
/**
* list of ratings for users.
*/
protected final Cv[] u_vs;
/**
* list ratings for items.
*/
protected final Cv[] i_vs;
/**
* Constructor that utilizes other PreferenceData object with default IdxPref to IdPref
* converters.
*
* @param preferences input preference data to be copied
* @param users user index
* @param items item index
* @param u_codec user preferences list CODEC
* @param i_codec item preferences list CODEC
* @param r_codec ratings CODEC
*/
public RatingCODECPreferenceData(FastPreferenceData<U, I> preferences,
FastUserIndex<U> users, FastItemIndex<I> items,
CODEC<Cu> u_codec, CODEC<Ci> i_codec, CODEC<Cv> r_codec) {
this(preferences, users, items, u_codec, i_codec, r_codec,
(Function<IdxPref, IdPref<I>> & Serializable) p -> new IdPref<>(items.iidx2item(p)),
(Function<IdxPref, IdPref<U>> & Serializable) p -> new IdPref<>(users.uidx2user(p)));
}
/**
* Constructor that utilizes other PreferenceData object with custom IdxPref to IdPref
* converters.
*
* @param preferences input preference data to be copied
* @param users user index
* @param items item index
* @param u_codec user preferences list CODEC
* @param i_codec item preferences list CODEC
* @param r_codec ratings CODEC
* @param uPrefFun user IdxPref to IdPref converter
* @param iPrefFun item IdxPref to IdPref converter
*/
public RatingCODECPreferenceData(FastPreferenceData<U, I> preferences,
FastUserIndex<U> users, FastItemIndex<I> items,
CODEC<Cu> u_codec, CODEC<Ci> i_codec, CODEC<Cv> r_codec,
Function<IdxPref, IdPref<I>> uPrefFun, Function<IdxPref, IdPref<U>> iPrefFun) {
this(ul(preferences), il(preferences), users, items, u_codec, i_codec, r_codec, uPrefFun, iPrefFun);
}
private static Stream<Tuple2io<int[][]>> ul(FastPreferenceData<?, ?> preferences) {
return preferences.getUidxWithPreferences().mapToObj(k -> {
IdxPref[] pairs = preferences.getUidxPreferences(k)
.sorted((p1, p2) -> Integer.compare(p1.v1, p2.v1))
.toArray(IdxPref[]::new);
int[] idxs = new int[pairs.length];
int[] vs = new int[pairs.length];
for (int i = 0; i < pairs.length; i++) {
idxs[i] = pairs[i].v1;
vs[i] = (int) pairs[i].v2;
}
return tuple(k, new int[][]{idxs, vs});
});
}
private static Stream<Tuple2io<int[][]>> il(FastPreferenceData<?, ?> preferences) {
return ul(new TransposedPreferenceData<>(preferences));
}
/**
* Constructor using streams of user and items preferences lists with default IdxPref to IdPref
* converters.
*
* @param ul stream of user preferences lists (id-rating)
* @param il stream of item preferences lists (id-rating)
* @param users user index
* @param items item index
* @param u_codec user preferences list CODEC
* @param i_codec item preferences list CODEC
* @param r_codec ratings CODEC
*/
@SuppressWarnings("unchecked")
public RatingCODECPreferenceData(Stream<Tuple2io<int[][]>> ul, Stream<Tuple2io<int[][]>> il,
FastUserIndex<U> users, FastItemIndex<I> items,
CODEC<Cu> u_codec, CODEC<Ci> i_codec, CODEC<Cv> r_codec) {
this(ul, il, users, items, u_codec, i_codec, r_codec,
(Function<IdxPref, IdPref<I>> & Serializable) p -> new IdPref<>(items.iidx2item(p)),
(Function<IdxPref, IdPref<U>> & Serializable) p -> new IdPref<>(users.uidx2user(p)));
}
/**
* Constructor using streams of user and items preferences lists with custom IdxPref to IdPref
* converters.
*
* @param ul stream of user preferences lists (id-rating)
* @param il stream of item preferences lists (id-rating)
* @param users user index
* @param items item index
* @param u_codec user preferences list CODEC
* @param i_codec item preferences list CODEC
* @param r_codec ratings CODEC
* @param uPrefFun user IdxPref to IdPref converter
* @param iPrefFun item IdxPref to IdPref converter
*/
public RatingCODECPreferenceData(Stream<Tuple2io<int[][]>> ul, Stream<Tuple2io<int[][]>> il,
FastUserIndex<U> users, FastItemIndex<I> items,
CODEC<Cu> u_codec, CODEC<Ci> i_codec, CODEC<Cv> r_codec,
Function<IdxPref, IdPref<I>> uPrefFun, Function<IdxPref, IdPref<U>> iPrefFun) {
this(users, items, u_codec, i_codec, r_codec, uPrefFun, iPrefFun);
index(ul, u_idxs, u_vs, u_len, u_codec, r_codec);
index(il, i_idxs, i_vs, i_len, i_codec, r_codec);
}
private static <Cx, Cv> void index(Stream<Tuple2io<int[][]>> lists, Cx[] idxs, Cv[] vs, int[] lens, CODEC<Cx> x_codec, CODEC<Cv> r_codec) {
lists.parallel().forEach(list -> {
int k = list.v1;
int[] _idxs = list.v2[0];
int[] _vs = list.v2[1];
lens[k] = _idxs.length;
if (!x_codec.isIntegrated()) {
delta(_idxs, 0, _idxs.length);
}
idxs[k] = x_codec.co(_idxs, 0, _idxs.length);
vs[k] = r_codec.co(_vs, 0, _vs.length);
});
}
/**
* Constructor custom IdxPref to IdPref converters that does not read any input data.
*
* @param users user index
* @param items item index
* @param u_codec user preferences list CODEC
* @param i_codec item preferences list CODEC
* @param r_codec ratings CODEC
* @param uPrefFun user IdxPref to IdPref converter
* @param iPrefFun item IdxPref to IdPref converter
*/
@SuppressWarnings("unchecked")
protected RatingCODECPreferenceData(FastUserIndex<U> users, FastItemIndex<I> items,
CODEC<Cu> u_codec, CODEC<Ci> i_codec, CODEC<Cv> r_codec,
Function<IdxPref, IdPref<I>> uPrefFun, Function<IdxPref, IdPref<U>> iPrefFun) {
super(users, items, u_codec, i_codec, uPrefFun, iPrefFun);
this.r_codec = r_codec;
this.u_vs = (Cv[]) new Object[users.numUsers()];
this.i_vs = (Cv[]) new Object[items.numItems()];
}
@Override
public DoubleIterator getUidxVs(final int uidx) {
return getVs(u_vs[uidx], u_len[uidx], r_codec);
}
@Override
public DoubleIterator getIidxVs(final int iidx) {
return getVs(i_vs[iidx], i_len[iidx], r_codec);
}
private static <Cv> DoubleIterator getVs(Cv cvs, int len, CODEC<Cv> r_codec) {
if (len == 0) {
return DoubleIterators.EMPTY_ITERATOR;
}
int[] vsi = new int[len];
r_codec.dec(cvs, vsi, 0, len);
double[] vsd = new double[len];
for (int i = 0; i < len; i++) {
vsd[i] = vsi[i];
}
return new ArrayDoubleIterator(vsd);
}
}