Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2012 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package android.bordeaux.services; |
| 17 | |
| 18 | import android.location.Location; |
| 19 | import android.text.format.Time; |
| 20 | import android.util.Log; |
| 21 | |
| 22 | import java.lang.Math; |
| 23 | import java.util.ArrayList; |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 24 | import java.util.HashMap; |
| 25 | import java.util.Map; |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 26 | |
| 27 | public class LocationCluster extends BaseCluster { |
| 28 | public static String TAG = "LocationCluster"; |
| 29 | |
| 30 | private static double FORGETTING_FACTOR = 0.1; |
| 31 | |
| 32 | private boolean mIsNewCluster; |
| 33 | |
| 34 | private ArrayList<Location> mLocations = new ArrayList<Location>(); |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 35 | private HashMap<String, Long> mNewHistogram = new HashMap<String, Long>(); |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 36 | |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 37 | // TODO: make it a singleton class |
| 38 | public LocationCluster(Location location, long duration, long avgInterval) { |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 39 | super(location, avgInterval); |
| 40 | mIsNewCluster = true; |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 41 | addSample(location, duration); |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 42 | } |
| 43 | |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 44 | public void addSample(Location location, long duration) { |
| 45 | updateTemporalHistogram(location.getTime(), duration); |
| 46 | |
| 47 | // use time field to store duation of this location |
| 48 | // TODO: extend Location class with additional field for this. |
| 49 | location.setTime(duration); |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 50 | mLocations.add(location); |
| 51 | } |
| 52 | |
| 53 | public void consolidate(long interval) { |
| 54 | // TODO: add check on interval |
| 55 | double[] newCenter = {0f, 0f, 0f}; |
| 56 | long newDuration = 0l; |
| 57 | |
| 58 | // update cluster center |
| 59 | for (Location location : mLocations) { |
| 60 | double[] vector = getLocationVector(location); |
Ruei-sung Lin | 83954e8 | 2012-08-28 18:00:48 -0700 | [diff] [blame^] | 61 | long duration = location.getTime(); // in seconds |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 62 | |
| 63 | newDuration += duration; |
| 64 | for (int i = 0; i < 3; ++i) { |
| 65 | newCenter[i] += vector[i] * duration; |
| 66 | } |
| 67 | } |
| 68 | for (int i = 0; i < 3; ++i) { |
| 69 | newCenter[i] /= newDuration; |
| 70 | } |
| 71 | // remove location data |
| 72 | mLocations.clear(); |
| 73 | |
| 74 | if (mIsNewCluster) { |
| 75 | for (int i = 0; i < 3; ++i) { |
| 76 | mCenter[i] = newCenter[i]; |
| 77 | } |
| 78 | mDuration = newDuration; |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 79 | mHistogram.clear(); |
| 80 | mHistogram.putAll(mNewHistogram); |
| 81 | mNewHistogram.clear(); |
| 82 | |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 83 | mIsNewCluster = false; |
| 84 | } else { |
| 85 | // the new center is weight average over latest and existing centers. |
| 86 | // fine tune the weight of new center |
| 87 | double newWeight = ((double) newDuration) / (newDuration + mDuration); |
| 88 | newWeight *= FORGETTING_FACTOR; |
| 89 | double currWeight = 1f - newWeight; |
| 90 | double norm = 0; |
| 91 | for (int i = 0; i < 3; ++i) { |
| 92 | mCenter[i] = currWeight * mCenter[i] + newWeight * newCenter[i]; |
| 93 | norm += mCenter[i] * mCenter[i]; |
| 94 | } |
| 95 | // normalize |
| 96 | for (int i = 0; i < 3; ++i) { |
| 97 | mCenter[i] /= norm; |
| 98 | } |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 99 | consolidateHistogram(newWeight, newDuration); |
| 100 | mNewHistogram.clear(); |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 101 | } |
| 102 | } |
| 103 | |
| 104 | /* |
| 105 | * if the new created cluster whose covered area overlaps with any existing |
| 106 | * cluster move the center away from that cluster till there is no overlap. |
| 107 | */ |
| 108 | public void moveAwayCluster(LocationCluster cluster, float distance) { |
| 109 | double[] vector = new double[3]; |
| 110 | |
| 111 | double dot = 0f; |
| 112 | for (int i = 0; i < 3; ++i) { |
| 113 | dot += mCenter[i] * cluster.mCenter[i]; |
| 114 | } |
| 115 | double norm = 0f; |
| 116 | for (int i = 0; i < 3; ++i) { |
| 117 | vector[i] = mCenter[i] - dot * cluster.mCenter[i]; |
| 118 | norm += vector[i] * vector[i]; |
| 119 | } |
| 120 | norm = Math.sqrt(norm); |
| 121 | |
| 122 | double radian = distance / EARTH_RADIUS; |
| 123 | for (int i = 0; i < 3; ++i) { |
| 124 | mCenter[i] = cluster.mCenter[i] * Math.cos(radian) + |
| 125 | (vector[i] / norm) * Math.sin(radian); |
| 126 | } |
| 127 | } |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 128 | |
| 129 | private void updateTemporalHistogram(long time, long duration) { |
| 130 | HashMap<String, String> timeFeatures = TimeStatsAggregator.getAllTimeFeatures(time); |
| 131 | |
Ruei-sung Lin | 83954e8 | 2012-08-28 18:00:48 -0700 | [diff] [blame^] | 132 | String timeOfWeek = timeFeatures.get(TimeStatsAggregator.TIME_OF_WEEK); |
| 133 | long totalDuration = (mNewHistogram.containsKey(timeOfWeek)) ? |
| 134 | mNewHistogram.get(timeOfWeek) + duration : duration; |
| 135 | mNewHistogram.put(timeOfWeek, totalDuration); |
| 136 | |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 137 | String timeOfDay = timeFeatures.get(TimeStatsAggregator.TIME_OF_DAY); |
Ruei-sung Lin | 83954e8 | 2012-08-28 18:00:48 -0700 | [diff] [blame^] | 138 | totalDuration = (mNewHistogram.containsKey(timeOfDay)) ? |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 139 | mNewHistogram.get(timeOfDay) + duration : duration; |
| 140 | mNewHistogram.put(timeOfDay, totalDuration); |
Ruei-sung Lin | 5d42ffa | 2012-08-23 16:01:57 -0700 | [diff] [blame] | 141 | } |
| 142 | |
| 143 | private void consolidateHistogram(double weight, long newDuration) { |
| 144 | long base = 1000; |
| 145 | long newWeight = (long) (weight * base); |
| 146 | long currWeight = base - newWeight; |
| 147 | |
| 148 | for (Map.Entry<String, Long> entry : mHistogram.entrySet()) { |
| 149 | String timeLabel = entry.getKey(); |
| 150 | long duration = entry.getValue() * currWeight; |
| 151 | if (mNewHistogram.containsKey(timeLabel)) { |
| 152 | duration += mNewHistogram.get(timeLabel) * newWeight; |
| 153 | } |
| 154 | duration /= base; |
| 155 | mHistogram.put(timeLabel, duration); |
| 156 | } |
| 157 | |
| 158 | for (Map.Entry<String, Long> entry : mNewHistogram.entrySet()) { |
| 159 | String timeLabel = entry.getKey(); |
| 160 | if (!mHistogram.containsKey(timeLabel)) { |
| 161 | long duration = newWeight * entry.getValue(); |
| 162 | duration /= base; |
| 163 | mHistogram.put(timeLabel, duration); |
| 164 | } |
| 165 | } |
| 166 | mDuration = (mDuration * currWeight + newDuration * newWeight) / base; |
| 167 | } |
Ruei-sung Lin | f0f7844 | 2012-08-13 19:04:29 -0700 | [diff] [blame] | 168 | } |