1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22
23 package org.hipparchus.util;
24
25 import java.util.NoSuchElementException;
26
27 import org.hipparchus.exception.LocalizedCoreFormats;
28 import org.hipparchus.exception.MathIllegalArgumentException;
29
30 /**
31 * Converter between unidimensional storage structure and multidimensional
32 * conceptual structure.
33 * This utility will convert from indices in a multidimensional structure
34 * to the corresponding index in a one-dimensional array. For example,
35 * assuming that the ranges (in 3 dimensions) of indices are 2, 4 and 3,
36 * the following correspondences, between 3-tuples indices and unidimensional
37 * indices, will hold:
38 * <ul>
39 * <li>(0, 0, 0) corresponds to 0</li>
40 * <li>(0, 0, 1) corresponds to 1</li>
41 * <li>(0, 0, 2) corresponds to 2</li>
42 * <li>(0, 1, 0) corresponds to 3</li>
43 * <li>...</li>
44 * <li>(1, 0, 0) corresponds to 12</li>
45 * <li>...</li>
46 * <li>(1, 3, 2) corresponds to 23</li>
47 * </ul>
48 */
49 public class MultidimensionalCounter implements Iterable<Integer> {
50 /**
51 * Number of dimensions.
52 */
53 private final int dimension;
54 /**
55 * Offset for each dimension.
56 */
57 private final int[] uniCounterOffset;
58 /**
59 * Counter sizes.
60 */
61 private final int[] size;
62 /**
63 * Total number of (one-dimensional) slots.
64 */
65 private final int totalSize;
66 /**
67 * Index of last dimension.
68 */
69 private final int last;
70
71 /**
72 * Perform iteration over the multidimensional counter.
73 */
74 public class Iterator implements java.util.Iterator<Integer> {
75 /**
76 * Multidimensional counter.
77 */
78 private final int[] counter = new int[dimension];
79 /**
80 * Unidimensional counter.
81 */
82 private int count = -1;
83 /**
84 * Maximum value for {@link #count}.
85 */
86 private final int maxCount = totalSize - 1;
87
88 /**
89 * Create an iterator
90 * @see #iterator()
91 */
92 Iterator() {
93 counter[last] = -1;
94 }
95
96 /**
97 * {@inheritDoc}
98 */
99 @Override
100 public boolean hasNext() {
101 return count < maxCount;
102 }
103
104 /**
105 * @return the unidimensional count after the counter has been
106 * incremented by {@code 1}.
107 * @throws NoSuchElementException if {@link #hasNext()} would have
108 * returned {@code false}.
109 */
110 @Override
111 public Integer next() {
112 if (!hasNext()) {
113 throw new NoSuchElementException();
114 }
115
116 for (int i = last; i >= 0; i--) {
117 if (counter[i] == size[i] - 1) {
118 counter[i] = 0;
119 } else {
120 ++counter[i];
121 break;
122 }
123 }
124
125 return ++count;
126 }
127
128 /**
129 * Get the current unidimensional counter slot.
130 *
131 * @return the index within the unidimensionl counter.
132 */
133 public int getCount() {
134 return count;
135 }
136 /**
137 * Get the current multidimensional counter slots.
138 *
139 * @return the indices within the multidimensional counter.
140 */
141 public int[] getCounts() {
142 return counter.clone();
143 }
144
145 /**
146 * Get the current count in the selected dimension.
147 *
148 * @param dim Dimension index.
149 * @return the count at the corresponding index for the current state
150 * of the iterator.
151 * @throws IndexOutOfBoundsException if {@code index} is not in the
152 * correct interval (as defined by the length of the argument in the
153 * {@link MultidimensionalCounter#MultidimensionalCounter(int[])
154 * constructor of the enclosing class}).
155 */
156 public int getCount(int dim) {
157 return counter[dim];
158 }
159
160 /** {@inheritDoc} */
161 @Override
162 public void remove() {
163 throw new UnsupportedOperationException();
164 }
165 }
166
167 /**
168 * Create a counter.
169 *
170 * @param size Counter sizes (number of slots in each dimension).
171 * @throws MathIllegalArgumentException if one of the sizes is
172 * negative or zero.
173 */
174 public MultidimensionalCounter(int... size) throws MathIllegalArgumentException {
175 dimension = size.length;
176 this.size = size.clone();
177
178 uniCounterOffset = new int[dimension];
179
180 last = dimension - 1;
181 int tS = size[last];
182 for (int i = 0; i < last; i++) {
183 int count = 1;
184 for (int j = i + 1; j < dimension; j++) {
185 count *= size[j];
186 }
187 uniCounterOffset[i] = count;
188 tS *= size[i];
189 }
190 uniCounterOffset[last] = 0;
191
192 if (tS <= 0) {
193 throw new MathIllegalArgumentException(LocalizedCoreFormats.NUMBER_TOO_SMALL_BOUND_EXCLUDED,
194 tS, 0);
195 }
196
197 totalSize = tS;
198 }
199
200 /**
201 * Create an iterator over this counter.
202 *
203 * @return the iterator.
204 */
205 @Override
206 public Iterator iterator() {
207 return new Iterator();
208 }
209
210 /**
211 * Get the number of dimensions of the multidimensional counter.
212 *
213 * @return the number of dimensions.
214 */
215 public int getDimension() {
216 return dimension;
217 }
218
219 /**
220 * Convert to multidimensional counter.
221 *
222 * @param index Index in unidimensional counter.
223 * @return the multidimensional counts.
224 * @throws MathIllegalArgumentException if {@code index} is not between
225 * {@code 0} and the value returned by {@link #getSize()} (excluded).
226 */
227 public int[] getCounts(int index) throws MathIllegalArgumentException {
228 MathUtils.checkRangeInclusive(index, 0, totalSize - 1);
229
230 final int[] indices = new int[dimension];
231
232 int count = 0;
233 for (int i = 0; i < last; i++) {
234 int idx = 0;
235 final int offset = uniCounterOffset[i];
236 while (count <= index) {
237 count += offset;
238 ++idx;
239 }
240 --idx;
241 count -= offset;
242 indices[i] = idx;
243 }
244
245 indices[last] = index - count;
246
247 return indices;
248 }
249
250 /**
251 * Convert to unidimensional counter.
252 *
253 * @param c Indices in multidimensional counter.
254 * @return the index within the unidimensionl counter.
255 * @throws MathIllegalArgumentException if the size of {@code c}
256 * does not match the size of the array given in the constructor.
257 * @throws MathIllegalArgumentException if a value of {@code c} is not in
258 * the range of the corresponding dimension, as defined in the
259 * {@link MultidimensionalCounter#MultidimensionalCounter(int...) constructor}.
260 */
261 public int getCount(int ... c) throws MathIllegalArgumentException {
262 MathUtils.checkDimension(c.length, dimension);
263 int count = 0;
264 for (int i = 0; i < dimension; i++) {
265 final int index = c[i];
266 MathUtils.checkRangeInclusive(index, 0, size[i] - 1);
267 count += uniCounterOffset[i] * c[i];
268 }
269 return count + c[last];
270 }
271
272 /**
273 * Get the total number of elements.
274 *
275 * @return the total size of the unidimensional counter.
276 */
277 public int getSize() {
278 return totalSize;
279 }
280 /**
281 * Get the number of multidimensional counter slots in each dimension.
282 *
283 * @return the sizes of the multidimensional counter in each dimension.
284 */
285 public int[] getSizes() {
286 return size.clone();
287 }
288
289 /**
290 * {@inheritDoc}
291 */
292 @Override
293 public String toString() {
294 final StringBuilder sb = new StringBuilder();
295 for (int i = 0; i < dimension; i++) {
296 sb.append('[').append(getCount(i)).append(']');
297 }
298 return sb.toString();
299 }
300 }