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
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
/*
* Copyright (C) 2012 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 android.bordeaux.services;
import android.location.Location;
import android.text.format.Time;
import android.util.Log;
import java.lang.Math;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
public class BaseCluster {
public static String TAG = "BaseCluster";
public double[] mCenter;
// protected double[] mCenter;
// Histogram illustrates the pattern of visit during time of day,
protected HashMap<String, Long> mHistogram = new HashMap<String, Long>();
protected long mAvgInterval;
protected long mDuration;
protected String mSemanticId;
protected static final double EARTH_RADIUS = 6378100f;
public BaseCluster(Location location, long avgInterval) {
mAvgInterval = avgInterval;
mCenter = getLocationVector(location);
mDuration = 0;
}
public BaseCluster() {
}
public String getSemanticId() {
return mSemanticId;
}
protected void generateSemanticId(long index) {
mSemanticId = "cluser: " + String.valueOf(index);
}
public void setSemanticId(String semanticId) {
mSemanticId = semanticId;
}
public boolean hasSemanticId() {
return mSemanticId != null;
}
protected double[] getLocationVector(Location location) {
return getLocationVector(location.getLongitude(), location.getLatitude());
}
protected double[] getLocationVector(double longitude, double latitude) {
double vector[] = new double[3];
double lambda = Math.toRadians(longitude);
double phi = Math.toRadians(latitude);
vector[0] = Math.cos(lambda) * Math.cos(phi);
vector[1] = Math.sin(lambda) * Math.cos(phi);
vector[2] = Math.sin(phi);
return vector;
}
protected double getCenterLongitude() {
// Because latitude ranges from -90 to 90 degrees, cosPhi >= 0.
double cosPhi = Math.cos(Math.asin(mCenter[2]));
double longitude = Math.toDegrees(Math.asin(mCenter[1] / cosPhi));
if (mCenter[0] < 0) {
longitude = (longitude > 0) ? 180f - longitude : -180 - longitude;
}
return longitude;
}
protected double getCenterLatitude() {
return Math.toDegrees(Math.asin(mCenter[2]));
}
private double computeDistance(double[] vector1, double[] vector2) {
double product = 0f;
for (int i = 0; i < 3; ++i) {
product += vector1[i] * vector2[i];
}
double radian = Math.acos(Math.min(product, 1f));
return radian * EARTH_RADIUS;
}
/*
* This computes the distance from loation to the cluster center in meter.
*/
public float distanceToCenter(Location location) {
return (float) computeDistance(mCenter, getLocationVector(location));
}
public float distanceToCluster(BaseCluster cluster) {
return (float) computeDistance(mCenter, cluster.mCenter);
}
public void absorbCluster(BaseCluster cluster) {
if (cluster.mAvgInterval != mAvgInterval) {
throw new RuntimeException(
"aborbing cluster failed: inconsistent average invergal ");
}
// the new cluster center is the average of the two clusters.
double currWeight = ((double) mDuration) / (mDuration + cluster.mDuration);
double newWeight = 1f - currWeight;
double norm = 0;
for (int i = 0; i < 3; ++i) {
mCenter[i] = currWeight * mCenter[i] + newWeight * cluster.mCenter[i];
norm += mCenter[i] * mCenter[i];
}
// normalize the center to be unit vector
for (int i = 0; i < 3; ++i) {
mCenter[i] /= norm;
}
absorbHistogram(cluster);
}
public void setCluster(BaseCluster cluster) {
for (int i = 0; i < 3; ++i) {
mCenter[i] = cluster.mCenter[i];
}
mHistogram.clear();
mHistogram.putAll(cluster.mHistogram);
mDuration = cluster.mDuration;
}
private void absorbHistogram(BaseCluster cluster) {
for (Map.Entry<String, Long> entry : cluster.mHistogram.entrySet()) {
String timeLabel = entry.getKey();
long duration = entry.getValue();
if (mHistogram.containsKey(timeLabel)) {
duration += mHistogram.get(timeLabel);
}
mHistogram.put(timeLabel, duration);
}
mDuration += cluster.mDuration;
}
public boolean passThreshold(long durationThreshold) {
// TODO: might want to keep semantic cluster
return mDuration > durationThreshold;
}
public final HashMap<String, Long> getHistogram() {
return mHistogram;
}
public void setHistogram(Map<String, Long> histogram) {
mHistogram.clear();
mHistogram.putAll(histogram);
mDuration = 0;
if (mHistogram.containsKey(TimeStatsAggregator.WEEKEND)) {
mDuration += mHistogram.get(TimeStatsAggregator.WEEKEND);
}
if (mHistogram.containsKey(TimeStatsAggregator.WEEKDAY)) {
mDuration += mHistogram.get(TimeStatsAggregator.WEEKDAY);
}
}
}
|
