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    }