blob: f4c4877d659af485deb2644b4c0b6c3d472bd09e (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed 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 com.android.tv.recommendation;
import java.util.concurrent.TimeUnit;
public class RecentChannelEvaluator extends Recommender.Evaluator {
private static final long WATCH_DURATION_MS_LOWER_BOUND = TimeUnit.MINUTES.toMillis(3);
private static final long WATCH_DURATION_MS_UPPER_BOUND = TimeUnit.MINUTES.toMillis(7);
private static final double MAX_SCORE_FOR_LOWER_BOUND = 0.1;
private long mLastWatchLogUpdateTimeMs;
public RecentChannelEvaluator() {
mLastWatchLogUpdateTimeMs = System.currentTimeMillis();
}
@Override
public void onNewWatchLog(ChannelRecord channelRecord) {
mLastWatchLogUpdateTimeMs = System.currentTimeMillis();
}
@Override
public double evaluateChannel(long channelId) {
ChannelRecord cr = getRecommender().getChannelRecord(channelId);
if (cr == null) {
return NOT_RECOMMENDED;
}
WatchedProgram[] watchHistory = cr.getWatchHistory();
double maxScore = 0.0;
for (int i = watchHistory.length - 1; i >= 0; --i) {
double recentWatchScore =
(double) watchHistory[i].getWatchEndTimeMs() / mLastWatchLogUpdateTimeMs;
double watchDurationScore;
double watchDuration = watchHistory[i].getWatchedDurationMs();
if (watchDuration < WATCH_DURATION_MS_LOWER_BOUND) {
watchDurationScore = MAX_SCORE_FOR_LOWER_BOUND;
} else if (watchDuration < WATCH_DURATION_MS_UPPER_BOUND) {
watchDurationScore =
(watchDuration - WATCH_DURATION_MS_LOWER_BOUND)
/ (WATCH_DURATION_MS_UPPER_BOUND
- WATCH_DURATION_MS_LOWER_BOUND)
* (1 - MAX_SCORE_FOR_LOWER_BOUND)
+ MAX_SCORE_FOR_LOWER_BOUND;
} else {
watchDurationScore = 1.0;
}
maxScore = Math.max(maxScore, watchDurationScore * recentWatchScore);
}
return (maxScore > 0.0) ? maxScore : NOT_RECOMMENDED;
}
}
|