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
|
package de.lmu.ifi.dbs.elki.algorithm.itemsetmining;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2014
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.Arrays;
import de.lmu.ifi.dbs.elki.data.BitVector;
import de.lmu.ifi.dbs.elki.data.type.VectorFieldTypeInformation;
import de.lmu.ifi.dbs.elki.utilities.BitsUtil;
import de.lmu.ifi.dbs.elki.utilities.exceptions.AbortException;
/**
* APRIORI itemset.
*
* @author Erich Schubert
*/
public class SparseItemset extends Itemset {
/**
* Items, as indexes.
*/
int[] indices;
/**
* Constructor.
*
* @param indices Items
*/
public SparseItemset(int[] indices) {
this.indices = indices;
}
/**
* Constructor.
*
* @param indices Items
* @param support Support
*/
public SparseItemset(int[] indices, int support) {
this.indices = indices;
this.support = support;
}
/**
* Constructor from existing itemsets.
*
* @param ii First 1-itemset
* @param ij Second 1-itemset
*/
public SparseItemset(OneItemset ii, OneItemset ij) {
if(ii.item == ij.item) {
throw new AbortException("SparseItemset constructed from identical 1-itemsets.");
}
this.indices = (ii.item < ij.item) ? new int[] { ii.item, ij.item } : new int[] { ij.item, ii.item };
}
@Override
public int length() {
return indices.length;
}
@Override
public boolean containedIn(BitVector bv) {
for(int item : indices) {
if(!bv.booleanValue(item)) {
return false;
}
}
return true;
}
@Override
public long[] getItems() {
long[] bits = BitsUtil.zero(indices[indices.length - 1]);
for(int item : indices) {
BitsUtil.setI(bits, item);
}
return bits;
}
@Override
public int hashCode() {
return Arrays.hashCode(indices);
}
@Override
public boolean equals(Object obj) {
if(this == obj) {
return true;
}
if(obj == null) {
return false;
}
if(!(obj instanceof Itemset) || ((Itemset) obj).length() != 1) {
return false;
}
// TODO: allow comparing to DenseItemset etc?
if(getClass() != obj.getClass()) {
return false;
}
return Arrays.equals(indices, ((SparseItemset) obj).indices);
}
@Override
public int compareTo(Itemset o) {
int cmp = Integer.compare(indices.length, o.length());
if(cmp != 0) {
return cmp;
}
SparseItemset other = (SparseItemset) o;
for(int i = 0; i < indices.length; i++) {
int c = Integer.compare(indices[i], other.indices[i]);
if(c != 0) {
return c;
}
}
return 0;
}
@Override
public StringBuilder appendTo(StringBuilder buf, VectorFieldTypeInformation<BitVector> meta) {
for(int j = 0; j < indices.length; j++) {
if(j > 0) {
buf.append(", ");
}
String lbl = (meta != null) ? meta.getLabel(indices[j]) : null;
if(lbl == null) {
buf.append(indices[j]);
}
else {
buf.append(lbl);
}
}
buf.append(": ").append(support);
return buf;
}
/**
* Perform the prefix test for sparse itemset.
*
* @param other Other itemset
* @return {@code true} iff the first n-1 items agree.
*/
public boolean prefixTest(SparseItemset other) {
if(indices.length != other.indices.length) {
throw new AbortException("PrefixTest is only valid for itemsets of the same length!");
}
for(int k = indices.length - 2; k >= 0; k--) {
if(indices[k] != other.indices[k]) {
return false;
}
}
return true;
}
}
|
