| /* |
| * 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; |
| } |
| } |