    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    import org.apache.commons.math.exception.util.LocalizedFormats;
    027
    028    /**
    029     * Maintains a frequency distribution.
    030     * <p>
    031     * Accepts int, long, char or Comparable values.  New values added must be
    032     * comparable to those that have been added, otherwise the add method will
    033     * throw an IllegalArgumentException.</p>
    034     * <p>
    035     * Integer values (int, long, Integer, Long) are not distinguished by type --
    036     * i.e. <code>addValue(Long.valueOf(2)), addValue(2), addValue(2l)</code> all have
    037     * the same effect (similarly for arguments to <code>getCount,</code> etc.).</p>
    038     * <p>
    039     * char values are converted by <code>addValue</code> to Character instances.
    040     * As such, these values are not comparable to integral values, so attempts
    041     * to combine integral types with chars in a frequency distribution will fail.
    042     * </p>
    043     * <p>
    044     * The values are ordered using the default (natural order), unless a
    045     * <code>Comparator</code> is supplied in the constructor.</p>
    046     *
    047     * @version $Revision: 1054186 $ $Date: 2011-01-01 03:28:46 +0100 (sam. 01 janv. 2011) $
    048     */
    049    public class Frequency implements Serializable {
    050
    051        /** Serializable version identifier */
    052        private static final long serialVersionUID = -3845586908418844111L;
    053
    054        /** underlying collection */
    055        private final TreeMap<Comparable<?>, Long> freqTable;
    056
    057        /**
    058         * Default constructor.
    059         */
    060        public Frequency() {
    061            freqTable = new TreeMap<Comparable<?>, Long>();
    062        }
    063
    064        /**
    065         * Constructor allowing values Comparator to be specified.
    066         *
    067         * @param comparator Comparator used to order values
    068         */
    069        @SuppressWarnings("unchecked") // TODO is the cast OK?
    070        public Frequency(Comparator<?> comparator) {
    071            freqTable = new TreeMap<Comparable<?>, Long>((Comparator<? super Comparable<?>>) comparator);
    072        }
    073
    074        /**
    075         * Return a string representation of this frequency
    076         * distribution.
    077         *
    078         * @return a string representation.
    079         */
    080        @Override
    081        public String toString() {
    082            NumberFormat nf = NumberFormat.getPercentInstance();
    083            StringBuilder outBuffer = new StringBuilder();
    084            outBuffer.append("Value \t Freq. \t Pct. \t Cum Pct. \n");
    085            Iterator<Comparable<?>> iter = freqTable.keySet().iterator();
    086            while (iter.hasNext()) {
    087                Comparable<?> value = iter.next();
    088                outBuffer.append(value);
    089                outBuffer.append('\t');
    090                outBuffer.append(getCount(value));
    091                outBuffer.append('\t');
    092                outBuffer.append(nf.format(getPct(value)));
    093                outBuffer.append('\t');
    094                outBuffer.append(nf.format(getCumPct(value)));
    095                outBuffer.append('\n');
    096            }
    097            return outBuffer.toString();
    098        }
    099
    100        /**
    101         * Adds 1 to the frequency count for v.
    102         * <p>
    103         * If other objects have already been added to this Frequency, v must
    104         * be comparable to those that have already been added.
    105         * </p>
    106         *
    107         * @param v the value to add.
    108         * @throws IllegalArgumentException if <code>v</code> is not Comparable,
    109         *         or is not comparable with previous entries
    110         * @deprecated use {@link #addValue(Comparable)} instead
    111         */
    112        @Deprecated
    113        public void addValue(Object v) {
    114            if (v instanceof Comparable<?>){
    115                addValue((Comparable<?>) v);
    116            } else {
    117                throw MathRuntimeException.createIllegalArgumentException(
    118                      LocalizedFormats.CLASS_DOESNT_IMPLEMENT_COMPARABLE,
    119                      v.getClass().getName());
    120            }
    121        }
    122
    123        /**
    124         * Adds 1 to the frequency count for v.
    125         * <p>
    126         * If other objects have already been added to this Frequency, v must
    127         * be comparable to those that have already been added.
    128         * </p>
    129         *
    130         * @param v the value to add.
    131         * @throws IllegalArgumentException if <code>v</code> is not comparable with previous entries
    132         */
    133        public void addValue(Comparable<?> v){
    134            Comparable<?> obj = v;
    135            if (v instanceof Integer) {
    136               obj = Long.valueOf(((Integer) v).longValue());
    137            }
    138            try {
    139                Long count = freqTable.get(obj);
    140                if (count == null) {
    141                    freqTable.put(obj, Long.valueOf(1));
    142                } else {
    143                    freqTable.put(obj, Long.valueOf(count.longValue() + 1));
    144                }
    145            } catch (ClassCastException ex) {
    146                //TreeMap will throw ClassCastException if v is not comparable
    147                throw MathRuntimeException.createIllegalArgumentException(
    148                      LocalizedFormats.INSTANCES_NOT_COMPARABLE_TO_EXISTING_VALUES,
    149                      v.getClass().getName());
    150            }
    151        }
    152
    153        /**
    154         * Adds 1 to the frequency count for v.
    155         *
    156         * @param v the value to add.
    157         */
    158        public void addValue(int v) {
    159            addValue(Long.valueOf(v));
    160        }
    161
    162        /**
    163         * Adds 1 to the frequency count for v.
    164         *
    165         * @param v the value to add.
    166         * @deprecated to be removed in math 3.0
    167         */
    168        @Deprecated
    169        public void addValue(Integer v) {
    170            addValue(Long.valueOf(v.longValue()));
    171        }
    172
    173        /**
    174         * Adds 1 to the frequency count for v.
    175         *
    176         * @param v the value to add.
    177         */
    178        public void addValue(long v) {
    179            addValue(Long.valueOf(v));
    180        }
    181
    182        /**
    183         * Adds 1 to the frequency count for v.
    184         *
    185         * @param v the value to add.
    186         */
    187        public void addValue(char v) {
    188            addValue(Character.valueOf(v));
    189        }
    190
    191        /** Clears the frequency table */
    192        public void clear() {
    193            freqTable.clear();
    194        }
    195
    196        /**
    197         * Returns an Iterator over the set of values that have been added.
    198         * <p>
    199         * If added values are integral (i.e., integers, longs, Integers, or Longs),
    200         * they are converted to Longs when they are added, so the objects returned
    201         * by the Iterator will in this case be Longs.</p>
    202         *
    203         * @return values Iterator
    204         */
    205        public Iterator<Comparable<?>> valuesIterator() {
    206            return freqTable.keySet().iterator();
    207        }
    208
    209        //-------------------------------------------------------------------------
    210
    211        /**
    212         * Returns the sum of all frequencies.
    213         *
    214         * @return the total frequency count.
    215         */
    216        public long getSumFreq() {
    217            long result = 0;
    218            Iterator<Long> iterator = freqTable.values().iterator();
    219            while (iterator.hasNext())  {
    220                result += iterator.next().longValue();
    221            }
    222            return result;
    223        }
    224
    225        /**
    226         * Returns the number of values = v.
    227         * Returns 0 if the value is not comparable.
    228         *
    229         * @param v the value to lookup.
    230         * @return the frequency of v.
    231         * @deprecated replaced by {@link #getCount(Comparable)} as of 2.0
    232         */
    233        @Deprecated
    234        public long getCount(Object v) {
    235            return getCount((Comparable<?>) v);
    236        }
    237
    238        /**
    239         * Returns the number of values = v.
    240         * Returns 0 if the value is not comparable.
    241         *
    242         * @param v the value to lookup.
    243         * @return the frequency of v.
    244         */
    245        public long getCount(Comparable<?> v) {
    246            if (v instanceof Integer) {
    247                return getCount(((Integer) v).longValue());
    248            }
    249            long result = 0;
    250            try {
    251                Long count =  freqTable.get(v);
    252                if (count != null) {
    253                    result = count.longValue();
    254                }
    255            } catch (ClassCastException ex) {
    256                // ignore and return 0 -- ClassCastException will be thrown if value is not comparable
    257            }
    258            return result;
    259        }
    260
    261        /**
    262         * Returns the number of values = v.
    263         *
    264         * @param v the value to lookup.
    265         * @return the frequency of v.
    266         */
    267        public long getCount(int v) {
    268            return getCount(Long.valueOf(v));
    269        }
    270
    271        /**
    272         * Returns the number of values = v.
    273         *
    274         * @param v the value to lookup.
    275         * @return the frequency of v.
    276         */
    277        public long getCount(long v) {
    278            return getCount(Long.valueOf(v));
    279        }
    280
    281        /**
    282         * Returns the number of values = v.
    283         *
    284         * @param v the value to lookup.
    285         * @return the frequency of v.
    286         */
    287        public long getCount(char v) {
    288            return getCount(Character.valueOf(v));
    289        }
    290
    291        /**
    292         * Returns the number of values in the frequency table.
    293         *
    294         * @return the number of unique values that have been added to the frequency table.
    295         * @see #valuesIterator()
    296         */
    297        public int getUniqueCount(){
    298            return freqTable.keySet().size();
    299        }
    300
    301        //-------------------------------------------------------------
    302
    303        /**
    304          * Returns the percentage of values that are equal to v
    305         * (as a proportion between 0 and 1).
    306         * <p>
    307         * Returns <code>Double.NaN</code> if no values have been added.</p>
    308         *
    309         * @param v the value to lookup
    310         * @return the proportion of values equal to v
    311         * @deprecated replaced by {@link #getPct(Comparable)} as of 2.0
    312         */
    313        @Deprecated
    314        public double getPct(Object v) {
    315            return getPct((Comparable<?>) v);
    316        }
    317
    318        /**
    319         * Returns the percentage of values that are equal to v
    320         * (as a proportion between 0 and 1).
    321         * <p>
    322         * Returns <code>Double.NaN</code> if no values have been added.</p>
    323         *
    324         * @param v the value to lookup
    325         * @return the proportion of values equal to v
    326         */
    327        public double getPct(Comparable<?> v) {
    328            final long sumFreq = getSumFreq();
    329            if (sumFreq == 0) {
    330                return Double.NaN;
    331            }
    332            return (double) getCount(v) / (double) sumFreq;
    333        }
    334
    335        /**
    336         * Returns the percentage of values that are equal to v
    337         * (as a proportion between 0 and 1).
    338         *
    339         * @param v the value to lookup
    340         * @return the proportion of values equal to v
    341         */
    342        public double getPct(int v) {
    343            return getPct(Long.valueOf(v));
    344        }
    345
    346        /**
    347         * Returns the percentage of values that are equal to v
    348         * (as a proportion between 0 and 1).
    349         *
    350         * @param v the value to lookup
    351         * @return the proportion of values equal to v
    352         */
    353        public double getPct(long v) {
    354            return getPct(Long.valueOf(v));
    355        }
    356
    357        /**
    358         * Returns the percentage of values that are equal to v
    359         * (as a proportion between 0 and 1).
    360         *
    361         * @param v the value to lookup
    362         * @return the proportion of values equal to v
    363         */
    364        public double getPct(char v) {
    365            return getPct(Character.valueOf(v));
    366        }
    367
    368        //-----------------------------------------------------------------------------------------
    369
    370        /**
    371         * Returns the cumulative frequency of values less than or equal to v.
    372         * <p>
    373         * Returns 0 if v is not comparable to the values set.</p>
    374         *
    375         * @param v the value to lookup.
    376         * @return the proportion of values equal to v
    377         * @deprecated replaced by {@link #getCumFreq(Comparable)} as of 2.0
    378         */
    379        @Deprecated
    380        public long getCumFreq(Object v) {
    381            return getCumFreq((Comparable<?>) v);
    382        }
    383
    384        /**
    385         * Returns the cumulative frequency of values less than or equal to v.
    386         * <p>
    387         * Returns 0 if v is not comparable to the values set.</p>
    388         *
    389         * @param v the value to lookup.
    390         * @return the proportion of values equal to v
    391         */
    392        public long getCumFreq(Comparable<?> v) {
    393            if (getSumFreq() == 0) {
    394                return 0;
    395            }
    396            if (v instanceof Integer) {
    397                return getCumFreq(((Integer) v).longValue());
    398            }
    399            @SuppressWarnings("unchecked") // OK, freqTable is Comparable<?>
    400            Comparator<Comparable<?>> c = (Comparator<Comparable<?>>) freqTable.comparator();
    401            if (c == null) {
    402                c = new NaturalComparator();
    403            }
    404            long result = 0;
    405
    406            try {
    407                Long value = freqTable.get(v);
    408                if (value != null) {
    409                    result = value.longValue();
    410                }
    411            } catch (ClassCastException ex) {
    412                return result;   // v is not comparable
    413            }
    414
    415            if (c.compare(v, freqTable.firstKey()) < 0) {
    416                return 0;  // v is comparable, but less than first value
    417            }
    418
    419            if (c.compare(v, freqTable.lastKey()) >= 0) {
    420                return getSumFreq();    // v is comparable, but greater than the last value
    421            }
    422
    423            Iterator<Comparable<?>> values = valuesIterator();
    424            while (values.hasNext()) {
    425                Comparable<?> nextValue = values.next();
    426                if (c.compare(v, nextValue) > 0) {
    427                    result += getCount(nextValue);
    428                } else {
    429                    return result;
    430                }
    431            }
    432            return result;
    433        }
    434
    435         /**
    436         * Returns the cumulative frequency of values less than or equal to v.
    437         * <p>
    438         * Returns 0 if v is not comparable to the values set.</p>
    439         *
    440         * @param v the value to lookup
    441         * @return the proportion of values equal to v
    442         */
    443        public long getCumFreq(int v) {
    444            return getCumFreq(Long.valueOf(v));
    445        }
    446
    447         /**
    448         * Returns the cumulative frequency of values less than or equal to v.
    449         * <p>
    450         * Returns 0 if v is not comparable to the values set.</p>
    451         *
    452         * @param v the value to lookup
    453         * @return the proportion of values equal to v
    454         */
    455        public long getCumFreq(long v) {
    456            return getCumFreq(Long.valueOf(v));
    457        }
    458
    459        /**
    460         * Returns the cumulative frequency of values less than or equal to v.
    461         * <p>
    462         * Returns 0 if v is not comparable to the values set.</p>
    463         *
    464         * @param v the value to lookup
    465         * @return the proportion of values equal to v
    466         */
    467        public long getCumFreq(char v) {
    468            return getCumFreq(Character.valueOf(v));
    469        }
    470
    471        //----------------------------------------------------------------------------------------------
    472
    473        /**
    474         * Returns the cumulative percentage of values less than or equal to v
    475         * (as a proportion between 0 and 1).
    476         * <p>
    477         * Returns <code>Double.NaN</code> if no values have been added.
    478         * Returns 0 if at least one value has been added, but v is not comparable
    479         * to the values set.</p>
    480         *
    481         * @param v the value to lookup
    482         * @return the proportion of values less than or equal to v
    483         * @deprecated replaced by {@link #getCumPct(Comparable)} as of 2.0
    484         */
    485        @Deprecated
    486        public double getCumPct(Object v) {
    487            return getCumPct((Comparable<?>) v);
    488
    489        }
    490
    491        /**
    492         * Returns the cumulative percentage of values less than or equal to v
    493         * (as a proportion between 0 and 1).
    494         * <p>
    495         * Returns <code>Double.NaN</code> if no values have been added.
    496         * Returns 0 if at least one value has been added, but v is not comparable
    497         * to the values set.</p>
    498         *
    499         * @param v the value to lookup
    500         * @return the proportion of values less than or equal to v
    501         */
    502        public double getCumPct(Comparable<?> v) {
    503            final long sumFreq = getSumFreq();
    504            if (sumFreq == 0) {
    505                return Double.NaN;
    506            }
    507            return (double) getCumFreq(v) / (double) sumFreq;
    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(int 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(long v) {
    533            return getCumPct(Long.valueOf(v));
    534        }
    535
    536        /**
    537         * Returns the cumulative percentage of values less than or equal to v
    538         * (as a proportion between 0 and 1).
    539         * <p>
    540         * Returns 0 if v is not comparable to the values set.</p>
    541         *
    542         * @param v the value to lookup
    543         * @return the proportion of values less than or equal to v
    544         */
    545        public double getCumPct(char v) {
    546            return getCumPct(Character.valueOf(v));
    547        }
    548
    549        /**
    550         * A Comparator that compares comparable objects using the
    551         * natural order.  Copied from Commons Collections ComparableComparator.
    552         */
    553        private static class NaturalComparator<T extends Comparable<T>> implements Comparator<Comparable<T>>, Serializable {
    554
    555            /** Serializable version identifier */
    556            private static final long serialVersionUID = -3852193713161395148L;
    557
    558            /**
    559             * Compare the two {@link Comparable Comparable} arguments.
    560             * This method is equivalent to:
    561             * <pre>(({@link Comparable Comparable})o1).{@link Comparable#compareTo compareTo}(o2)</pre>
    562             *
    563             * @param  o1 the first object
    564             * @param  o2 the second object
    565             * @return  result of comparison
    566             * @throws NullPointerException when <i>o1</i> is <code>null</code>,
    567             *         or when <code>((Comparable)o1).compareTo(o2)</code> does
    568             * @throws ClassCastException when <i>o1</i> is not a {@link Comparable Comparable},
    569             *         or when <code>((Comparable)o1).compareTo(o2)</code> does
    570             */
    571            @SuppressWarnings("unchecked") // cast to (T) may throw ClassCastException, see Javadoc
    572            public int compare(Comparable<T> o1, Comparable<T> o2) {
    573                return o1.compareTo((T) o2);
    574            }
    575        }
    576
    577        /** {@inheritDoc} */
    578        @Override
    579        public int hashCode() {
    580            final int prime = 31;
    581            int result = 1;
    582            result = prime * result +
    583                     ((freqTable == null) ? 0 : freqTable.hashCode());
    584            return result;
    585        }
    586
    587        /** {@inheritDoc} */
    588        @Override
    589        public boolean equals(Object obj) {
    590            if (this == obj)
    591                return true;
    592            if (!(obj instanceof Frequency))
    593                return false;
    594            Frequency other = (Frequency) obj;
    595            if (freqTable == null) {
    596                if (other.freqTable != null)
    597                    return false;
    598            } else if (!freqTable.equals(other.freqTable))
    599                return false;
    600            return true;
    601        }
    602
    603    }