001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math.stat;
018
019 import java.io.Serializable;
020 import java.text.NumberFormat;
021 import java.util.Iterator;
022 import java.util.Comparator;
023 import java.util.TreeMap;
024
025 import org.apache.commons.math.MathRuntimeException;
026
027 /**
028 * Maintains a frequency distribution.
029 * <p>
030 * Accepts int, long, char or Comparable values. New values added must be
031 * comparable to those that have been added, otherwise the add method will
032 * throw an IllegalArgumentException.</p>
033 * <p>
034 * Integer values (int, long, Integer, Long) are not distinguished by type --
035 * i.e. <code>addValue(Long.valueOf(2)), addValue(2), addValue(2l)</code> all have
036 * the same effect (similarly for arguments to <code>getCount,</code> etc.).</p>
037 * <p>
038 * char values are converted by <code>addValue</code> to Character instances.
039 * As such, these values are not comparable to integral values, so attempts
040 * to combine integral types with chars in a frequency distribution will fail.
041 * </p>
042 * <p>
043 * The values are ordered using the default (natural order), unless a
044 * <code>Comparator</code> is supplied in the constructor.</p>
045 *
046 * @version $Revision: 791733 $ $Date: 2009-07-07 03:44:52 -0400 (Tue, 07 Jul 2009) $
047 */
048 public class Frequency implements Serializable {
049
050 /** Serializable version identifier */
051 private static final long serialVersionUID = -3845586908418844111L;
052
053 /** underlying collection */
054 private final TreeMap<Comparable<?>, Long> freqTable;
055
056 /**
057 * Default constructor.
058 */
059 public Frequency() {
060 freqTable = new TreeMap<Comparable<?>, Long>();
061 }
062
063 /**
064 * Constructor allowing values Comparator to be specified.
065 *
066 * @param comparator Comparator used to order values
067 */
068 @SuppressWarnings("unchecked")
069 public Frequency(Comparator<?> comparator) {
070 freqTable = new TreeMap<Comparable<?>, Long>((Comparator<? super Comparable<?>>) comparator);
071 }
072
073 /**
074 * Return a string representation of this frequency
075 * distribution.
076 *
077 * @return a string representation.
078 */
079 @Override
080 public String toString() {
081 NumberFormat nf = NumberFormat.getPercentInstance();
082 StringBuffer outBuffer = new StringBuffer();
083 outBuffer.append("Value \t Freq. \t Pct. \t Cum Pct. \n");
084 Iterator<Comparable<?>> iter = freqTable.keySet().iterator();
085 while (iter.hasNext()) {
086 Comparable<?> value = iter.next();
087 outBuffer.append(value);
088 outBuffer.append('\t');
089 outBuffer.append(getCount(value));
090 outBuffer.append('\t');
091 outBuffer.append(nf.format(getPct(value)));
092 outBuffer.append('\t');
093 outBuffer.append(nf.format(getCumPct(value)));
094 outBuffer.append('\n');
095 }
096 return outBuffer.toString();
097 }
098
099 /**
100 * Adds 1 to the frequency count for v.
101 * <p>
102 * If other objects have already been added to this Frequency, v must
103 * be comparable to those that have already been added.
104 * </p>
105 *
106 * @param v the value to add.
107 * @throws IllegalArgumentException if <code>v</code> is not Comparable,
108 * or is not comparable with previous entries
109 * @deprecated use {@link #addValue(Comparable)} instead
110 */
111 @Deprecated
112 public void addValue(Object v) {
113 if (v instanceof Comparable<?>){
114 addValue((Comparable<?>) v);
115 } else {
116 throw MathRuntimeException.createIllegalArgumentException(
117 "class ({0}) does not implement Comparable",
118 v.getClass().getName());
119 }
120 }
121
122 /**
123 * Adds 1 to the frequency count for v.
124 * <p>
125 * If other objects have already been added to this Frequency, v must
126 * be comparable to those that have already been added.
127 * </p>
128 *
129 * @param v the value to add.
130 * @throws IllegalArgumentException if <code>v</code> is not comparable with previous entries
131 */
132 public void addValue(Comparable<?> v){
133 Comparable<?> obj = v;
134 if (v instanceof Integer) {
135 obj = Long.valueOf(((Integer) v).longValue());
136 }
137 try {
138 Long count = freqTable.get(obj);
139 if (count == null) {
140 freqTable.put(obj, Long.valueOf(1));
141 } else {
142 freqTable.put(obj, Long.valueOf(count.longValue() + 1));
143 }
144 } catch (ClassCastException ex) {
145 //TreeMap will throw ClassCastException if v is not comparable
146 throw MathRuntimeException.createIllegalArgumentException(
147 "instance of class {0} not comparable to existing values",
148 v.getClass().getName());
149 }
150 }
151
152 /**
153 * Adds 1 to the frequency count for v.
154 *
155 * @param v the value to add.
156 */
157 public void addValue(int v) {
158 addValue(Long.valueOf(v));
159 }
160
161 /**
162 * Adds 1 to the frequency count for v.
163 *
164 * @param v the value to add.
165 */
166 public void addValue(Integer v) {
167 addValue(Long.valueOf(v.longValue()));
168 }
169
170 /**
171 * Adds 1 to the frequency count for v.
172 *
173 * @param v the value to add.
174 */
175 public void addValue(long v) {
176 addValue(Long.valueOf(v));
177 }
178
179 /**
180 * Adds 1 to the frequency count for v.
181 *
182 * @param v the value to add.
183 */
184 public void addValue(char v) {
185 addValue(Character.valueOf(v));
186 }
187
188 /** Clears the frequency table */
189 public void clear() {
190 freqTable.clear();
191 }
192
193 /**
194 * Returns an Iterator over the set of values that have been added.
195 * <p>
196 * If added values are integral (i.e., integers, longs, Integers, or Longs),
197 * they are converted to Longs when they are added, so the objects returned
198 * by the Iterator will in this case be Longs.</p>
199 *
200 * @return values Iterator
201 */
202 public Iterator<Comparable<?>> valuesIterator() {
203 return freqTable.keySet().iterator();
204 }
205
206 //-------------------------------------------------------------------------
207
208 /**
209 * Returns the sum of all frequencies.
210 *
211 * @return the total frequency count.
212 */
213 public long getSumFreq() {
214 long result = 0;
215 Iterator<Long> iterator = freqTable.values().iterator();
216 while (iterator.hasNext()) {
217 result += iterator.next().longValue();
218 }
219 return result;
220 }
221
222 /**
223 * Returns the number of values = v.
224 * Returns 0 if the value is not comparable.
225 *
226 * @param v the value to lookup.
227 * @return the frequency of v.
228 * @deprecated replaced by {@link #getCount(Comparable)} as of 2.0
229 */
230 @Deprecated
231 public long getCount(Object v) {
232 return getCount((Comparable<?>) v);
233 }
234
235 /**
236 * Returns the number of values = v.
237 * Returns 0 if the value is not comparable.
238 *
239 * @param v the value to lookup.
240 * @return the frequency of v.
241 */
242 public long getCount(Comparable<?> v) {
243 if (v instanceof Integer) {
244 return getCount(((Integer) v).longValue());
245 }
246 long result = 0;
247 try {
248 Long count = freqTable.get(v);
249 if (count != null) {
250 result = count.longValue();
251 }
252 } catch (ClassCastException ex) {
253 // ignore and return 0 -- ClassCastException will be thrown if value is not comparable
254 }
255 return result;
256 }
257
258 /**
259 * Returns the number of values = v.
260 *
261 * @param v the value to lookup.
262 * @return the frequency of v.
263 */
264 public long getCount(int v) {
265 return getCount(Long.valueOf(v));
266 }
267
268 /**
269 * Returns the number of values = v.
270 *
271 * @param v the value to lookup.
272 * @return the frequency of v.
273 */
274 public long getCount(long v) {
275 return getCount(Long.valueOf(v));
276 }
277
278 /**
279 * Returns the number of values = v.
280 *
281 * @param v the value to lookup.
282 * @return the frequency of v.
283 */
284 public long getCount(char v) {
285 return getCount(Character.valueOf(v));
286 }
287
288 //-------------------------------------------------------------
289
290 /**
291 * Returns the percentage of values that are equal to v
292 * (as a proportion between 0 and 1).
293 * <p>
294 * Returns <code>Double.NaN</code> if no values have been added.</p>
295 *
296 * @param v the value to lookup
297 * @return the proportion of values equal to v
298 * @deprecated replaced by {@link #getPct(Comparable)} as of 2.0
299 */
300 @Deprecated
301 public double getPct(Object v) {
302 return getCumPct((Comparable<?>) v);
303 }
304
305 /**
306 * Returns the percentage of values that are equal to v
307 * (as a proportion between 0 and 1).
308 * <p>
309 * Returns <code>Double.NaN</code> if no values have been added.</p>
310 *
311 * @param v the value to lookup
312 * @return the proportion of values equal to v
313 */
314 public double getPct(Comparable<?> v) {
315 final long sumFreq = getSumFreq();
316 if (sumFreq == 0) {
317 return Double.NaN;
318 }
319 return (double) getCount(v) / (double) sumFreq;
320 }
321
322 /**
323 * Returns the percentage of values that are equal to v
324 * (as a proportion between 0 and 1).
325 *
326 * @param v the value to lookup
327 * @return the proportion of values equal to v
328 */
329 public double getPct(int v) {
330 return getPct(Long.valueOf(v));
331 }
332
333 /**
334 * Returns the percentage of values that are equal to v
335 * (as a proportion between 0 and 1).
336 *
337 * @param v the value to lookup
338 * @return the proportion of values equal to v
339 */
340 public double getPct(long v) {
341 return getPct(Long.valueOf(v));
342 }
343
344 /**
345 * Returns the percentage of values that are equal to v
346 * (as a proportion between 0 and 1).
347 *
348 * @param v the value to lookup
349 * @return the proportion of values equal to v
350 */
351 public double getPct(char v) {
352 return getPct(Character.valueOf(v));
353 }
354
355 //-----------------------------------------------------------------------------------------
356
357 /**
358 * Returns the cumulative frequency of values less than or equal to v.
359 * <p>
360 * Returns 0 if v is not comparable to the values set.</p>
361 *
362 * @param v the value to lookup.
363 * @return the proportion of values equal to v
364 * @deprecated replaced by {@link #getCumFreq(Comparable)} as of 2.0
365 */
366 @Deprecated
367 public long getCumFreq(Object v) {
368 return getCumFreq((Comparable<?>) v);
369 }
370
371 /**
372 * Returns the cumulative frequency of values less than or equal to v.
373 * <p>
374 * Returns 0 if v is not comparable to the values set.</p>
375 *
376 * @param v the value to lookup.
377 * @return the proportion of values equal to v
378 */
379 @SuppressWarnings("unchecked")
380 public long getCumFreq(Comparable<?> v) {
381 if (getSumFreq() == 0) {
382 return 0;
383 }
384 if (v instanceof Integer) {
385 return getCumFreq(((Integer) v).longValue());
386 }
387 Comparator<Comparable<?>> c = (Comparator<Comparable<?>>) freqTable.comparator();
388 if (c == null) {
389 c = new NaturalComparator();
390 }
391 long result = 0;
392
393 try {
394 Long value = freqTable.get(v);
395 if (value != null) {
396 result = value.longValue();
397 }
398 } catch (ClassCastException ex) {
399 return result; // v is not comparable
400 }
401
402 if (c.compare(v, freqTable.firstKey()) < 0) {
403 return 0; // v is comparable, but less than first value
404 }
405
406 if (c.compare(v, freqTable.lastKey()) >= 0) {
407 return getSumFreq(); // v is comparable, but greater than the last value
408 }
409
410 Iterator<Comparable<?>> values = valuesIterator();
411 while (values.hasNext()) {
412 Comparable<?> nextValue = values.next();
413 if (c.compare(v, nextValue) > 0) {
414 result += getCount(nextValue);
415 } else {
416 return result;
417 }
418 }
419 return result;
420 }
421
422 /**
423 * Returns the cumulative frequency of values less than or equal to v.
424 * <p>
425 * Returns 0 if v is not comparable to the values set.</p>
426 *
427 * @param v the value to lookup
428 * @return the proportion of values equal to v
429 */
430 public long getCumFreq(int v) {
431 return getCumFreq(Long.valueOf(v));
432 }
433
434 /**
435 * Returns the cumulative frequency of values less than or equal to v.
436 * <p>
437 * Returns 0 if v is not comparable to the values set.</p>
438 *
439 * @param v the value to lookup
440 * @return the proportion of values equal to v
441 */
442 public long getCumFreq(long v) {
443 return getCumFreq(Long.valueOf(v));
444 }
445
446 /**
447 * Returns the cumulative frequency of values less than or equal to v.
448 * <p>
449 * Returns 0 if v is not comparable to the values set.</p>
450 *
451 * @param v the value to lookup
452 * @return the proportion of values equal to v
453 */
454 public long getCumFreq(char v) {
455 return getCumFreq(Character.valueOf(v));
456 }
457
458 //----------------------------------------------------------------------------------------------
459
460 /**
461 * Returns the cumulative percentage of values less than or equal to v
462 * (as a proportion between 0 and 1).
463 * <p>
464 * Returns <code>Double.NaN</code> if no values have been added.
465 * Returns 0 if at least one value has been added, but v is not comparable
466 * to the values set.</p>
467 *
468 * @param v the value to lookup
469 * @return the proportion of values less than or equal to v
470 * @deprecated replaced by {@link #getCumPct(Comparable)} as of 2.0
471 */
472 @Deprecated
473 public double getCumPct(Object v) {
474 return getCumPct((Comparable<?>) v);
475
476 }
477
478 /**
479 * Returns the cumulative percentage of values less than or equal to v
480 * (as a proportion between 0 and 1).
481 * <p>
482 * Returns <code>Double.NaN</code> if no values have been added.
483 * Returns 0 if at least one value has been added, but v is not comparable
484 * to the values set.</p>
485 *
486 * @param v the value to lookup
487 * @return the proportion of values less than or equal to v
488 */
489 public double getCumPct(Comparable<?> v) {
490 final long sumFreq = getSumFreq();
491 if (sumFreq == 0) {
492 return Double.NaN;
493 }
494 return (double) getCumFreq(v) / (double) sumFreq;
495 }
496
497 /**
498 * Returns the cumulative percentage of values less than or equal to v
499 * (as a proportion between 0 and 1).
500 * <p>
501 * Returns 0 if v is not comparable to the values set.</p>
502 *
503 * @param v the value to lookup
504 * @return the proportion of values less than or equal to v
505 */
506 public double getCumPct(int v) {
507 return getCumPct(Long.valueOf(v));
508 }
509
510 /**
511 * Returns the cumulative percentage of values less than or equal to v
512 * (as a proportion between 0 and 1).
513 * <p>
514 * Returns 0 if v is not comparable to the values set.</p>
515 *
516 * @param v the value to lookup
517 * @return the proportion of values less than or equal to v
518 */
519 public double getCumPct(long v) {
520 return getCumPct(Long.valueOf(v));
521 }
522
523 /**
524 * Returns the cumulative percentage of values less than or equal to v
525 * (as a proportion between 0 and 1).
526 * <p>
527 * Returns 0 if v is not comparable to the values set.</p>
528 *
529 * @param v the value to lookup
530 * @return the proportion of values less than or equal to v
531 */
532 public double getCumPct(char v) {
533 return getCumPct(Character.valueOf(v));
534 }
535
536 /**
537 * A Comparator that compares comparable objects using the
538 * natural order. Copied from Commons Collections ComparableComparator.
539 */
540 private static class NaturalComparator<T extends Comparable<T>> implements Comparator<Comparable<T>>, Serializable {
541
542 /** Serializable version identifier */
543 private static final long serialVersionUID = -3852193713161395148L;
544
545 /**
546 * Compare the two {@link Comparable Comparable} arguments.
547 * This method is equivalent to:
548 * <pre>(({@link Comparable Comparable})o1).{@link Comparable#compareTo compareTo}(o2)</pre>
549 *
550 * @param o1 the first object
551 * @param o2 the second object
552 * @return result of comparison
553 * @throws NullPointerException when <i>o1</i> is <code>null</code>,
554 * or when <code>((Comparable)o1).compareTo(o2)</code> does
555 * @throws ClassCastException when <i>o1</i> is not a {@link Comparable Comparable},
556 * or when <code>((Comparable)o1).compareTo(o2)</code> does
557 */
558 @SuppressWarnings("unchecked")
559 public int compare(Comparable<T> o1, Comparable<T> o2) {
560 return (o1.compareTo((T) o2));
561 }
562 }
563
564 /** {@inheritDoc} */
565 @Override
566 public int hashCode() {
567 final int prime = 31;
568 int result = 1;
569 result = prime * result +
570 ((freqTable == null) ? 0 : freqTable.hashCode());
571 return result;
572 }
573
574 /** {@inheritDoc} */
575 @Override
576 public boolean equals(Object obj) {
577 if (this == obj)
578 return true;
579 if (obj == null)
580 return false;
581 if (!(obj instanceof Frequency))
582 return false;
583 Frequency other = (Frequency) obj;
584 if (freqTable == null) {
585 if (other.freqTable != null)
586 return false;
587 } else if (!freqTable.equals(other.freqTable))
588 return false;
589 return true;
590 }
591
592 }