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Diffstat (limited to 'src/main/java/org/apache/commons/math3/stat/Frequency.java')
| -rw-r--r-- | src/main/java/org/apache/commons/math3/stat/Frequency.java | 664 |
1 files changed, 664 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/stat/Frequency.java b/src/main/java/org/apache/commons/math3/stat/Frequency.java new file mode 100644 index 0000000..276382c --- /dev/null +++ b/src/main/java/org/apache/commons/math3/stat/Frequency.java @@ -0,0 +1,664 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.commons.math3.stat; + +import org.apache.commons.math3.exception.MathIllegalArgumentException; +import org.apache.commons.math3.exception.NullArgumentException; +import org.apache.commons.math3.exception.util.LocalizedFormats; +import org.apache.commons.math3.util.MathUtils; + +import java.io.Serializable; +import java.text.NumberFormat; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Comparator; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Map.Entry; +import java.util.SortedMap; +import java.util.TreeMap; + +/** + * Maintains a frequency distribution. + * + * <p>Accepts int, long, char or Comparable values. New values added must be comparable to those + * that have been added, otherwise the add method will throw an IllegalArgumentException. + * + * <p>Integer values (int, long, Integer, Long) are not distinguished by type -- i.e. <code> + * addValue(Long.valueOf(2)), addValue(2), addValue(2l)</code> all have the same effect (similarly + * for arguments to <code>getCount,</code> etc.). + * + * <p>NOTE: byte and short values will be implicitly converted to int values by the compiler, thus + * there are no explicit overloaded methods for these primitive types. + * + * <p>char values are converted by <code>addValue</code> to Character instances. As such, these + * values are not comparable to integral values, so attempts to combine integral types with chars in + * a frequency distribution will fail. + * + * <p>Float is not coerced to Double. Since they are not Comparable with each other the user must do + * any necessary coercion. Float.NaN and Double.NaN are not treated specially; they may occur in + * input and will occur in output if appropriate. </b> + * + * <p>The values are ordered using the default (natural order), unless a <code>Comparator</code> is + * supplied in the constructor. + */ +public class Frequency implements Serializable { + + /** Serializable version identifier */ + private static final long serialVersionUID = -3845586908418844111L; + + /** underlying collection */ + private final SortedMap<Comparable<?>, Long> freqTable; + + /** Default constructor. */ + public Frequency() { + freqTable = new TreeMap<Comparable<?>, Long>(); + } + + /** + * Constructor allowing values Comparator to be specified. + * + * @param comparator Comparator used to order values + */ + @SuppressWarnings("unchecked") // TODO is the cast OK? + public Frequency(Comparator<?> comparator) { + freqTable = + new TreeMap<Comparable<?>, Long>((Comparator<? super Comparable<?>>) comparator); + } + + /** + * Return a string representation of this frequency distribution. + * + * @return a string representation. + */ + @Override + public String toString() { + NumberFormat nf = NumberFormat.getPercentInstance(); + StringBuilder outBuffer = new StringBuilder(); + outBuffer.append("Value \t Freq. \t Pct. \t Cum Pct. \n"); + Iterator<Comparable<?>> iter = freqTable.keySet().iterator(); + while (iter.hasNext()) { + Comparable<?> value = iter.next(); + outBuffer.append(value); + outBuffer.append('\t'); + outBuffer.append(getCount(value)); + outBuffer.append('\t'); + outBuffer.append(nf.format(getPct(value))); + outBuffer.append('\t'); + outBuffer.append(nf.format(getCumPct(value))); + outBuffer.append('\n'); + } + return outBuffer.toString(); + } + + /** + * Adds 1 to the frequency count for v. + * + * <p>If other objects have already been added to this Frequency, v must be comparable to those + * that have already been added. + * + * @param v the value to add. + * @throws MathIllegalArgumentException if <code>v</code> is not comparable with previous + * entries + */ + public void addValue(Comparable<?> v) throws MathIllegalArgumentException { + incrementValue(v, 1); + } + + /** + * Adds 1 to the frequency count for v. + * + * @param v the value to add. + * @throws MathIllegalArgumentException if the table contains entries not comparable to Long + */ + public void addValue(int v) throws MathIllegalArgumentException { + addValue(Long.valueOf(v)); + } + + /** + * Adds 1 to the frequency count for v. + * + * @param v the value to add. + * @throws MathIllegalArgumentException if the table contains entries not comparable to Long + */ + public void addValue(long v) throws MathIllegalArgumentException { + addValue(Long.valueOf(v)); + } + + /** + * Adds 1 to the frequency count for v. + * + * @param v the value to add. + * @throws MathIllegalArgumentException if the table contains entries not comparable to Char + */ + public void addValue(char v) throws MathIllegalArgumentException { + addValue(Character.valueOf(v)); + } + + /** + * Increments the frequency count for v. + * + * <p>If other objects have already been added to this Frequency, v must be comparable to those + * that have already been added. + * + * @param v the value to add. + * @param increment the amount by which the value should be incremented + * @throws MathIllegalArgumentException if <code>v</code> is not comparable with previous + * entries + * @since 3.1 + */ + public void incrementValue(Comparable<?> v, long increment) + throws MathIllegalArgumentException { + Comparable<?> obj = v; + if (v instanceof Integer) { + obj = Long.valueOf(((Integer) v).longValue()); + } + try { + Long count = freqTable.get(obj); + if (count == null) { + freqTable.put(obj, Long.valueOf(increment)); + } else { + freqTable.put(obj, Long.valueOf(count.longValue() + increment)); + } + } catch (ClassCastException ex) { + // TreeMap will throw ClassCastException if v is not comparable + throw new MathIllegalArgumentException( + LocalizedFormats.INSTANCES_NOT_COMPARABLE_TO_EXISTING_VALUES, + v.getClass().getName()); + } + } + + /** + * Increments the frequency count for v. + * + * <p>If other objects have already been added to this Frequency, v must be comparable to those + * that have already been added. + * + * @param v the value to add. + * @param increment the amount by which the value should be incremented + * @throws MathIllegalArgumentException if the table contains entries not comparable to Long + * @since 3.3 + */ + public void incrementValue(int v, long increment) throws MathIllegalArgumentException { + incrementValue(Long.valueOf(v), increment); + } + + /** + * Increments the frequency count for v. + * + * <p>If other objects have already been added to this Frequency, v must be comparable to those + * that have already been added. + * + * @param v the value to add. + * @param increment the amount by which the value should be incremented + * @throws MathIllegalArgumentException if the table contains entries not comparable to Long + * @since 3.3 + */ + public void incrementValue(long v, long increment) throws MathIllegalArgumentException { + incrementValue(Long.valueOf(v), increment); + } + + /** + * Increments the frequency count for v. + * + * <p>If other objects have already been added to this Frequency, v must be comparable to those + * that have already been added. + * + * @param v the value to add. + * @param increment the amount by which the value should be incremented + * @throws MathIllegalArgumentException if the table contains entries not comparable to Char + * @since 3.3 + */ + public void incrementValue(char v, long increment) throws MathIllegalArgumentException { + incrementValue(Character.valueOf(v), increment); + } + + /** Clears the frequency table */ + public void clear() { + freqTable.clear(); + } + + /** + * Returns an Iterator over the set of values that have been added. + * + * <p>If added values are integral (i.e., integers, longs, Integers, or Longs), they are + * converted to Longs when they are added, so the objects returned by the Iterator will in this + * case be Longs. + * + * @return values Iterator + */ + public Iterator<Comparable<?>> valuesIterator() { + return freqTable.keySet().iterator(); + } + + /** + * Return an Iterator over the set of keys and values that have been added. Using the entry set + * to iterate is more efficient in the case where you need to access respective counts as well + * as values, since it doesn't require a "get" for every key...the value is provided in the + * Map.Entry. + * + * <p>If added values are integral (i.e., integers, longs, Integers, or Longs), they are + * converted to Longs when they are added, so the values of the map entries returned by the + * Iterator will in this case be Longs. + * + * @return entry set Iterator + * @since 3.1 + */ + public Iterator<Map.Entry<Comparable<?>, Long>> entrySetIterator() { + return freqTable.entrySet().iterator(); + } + + // ------------------------------------------------------------------------- + + /** + * Returns the sum of all frequencies. + * + * @return the total frequency count. + */ + public long getSumFreq() { + long result = 0; + Iterator<Long> iterator = freqTable.values().iterator(); + while (iterator.hasNext()) { + result += iterator.next().longValue(); + } + return result; + } + + /** + * Returns the number of values equal to v. Returns 0 if the value is not comparable. + * + * @param v the value to lookup. + * @return the frequency of v. + */ + public long getCount(Comparable<?> v) { + if (v instanceof Integer) { + return getCount(((Integer) v).longValue()); + } + long result = 0; + try { + Long count = freqTable.get(v); + if (count != null) { + result = count.longValue(); + } + } catch (ClassCastException ex) { // NOPMD + // ignore and return 0 -- ClassCastException will be thrown if value is not comparable + } + return result; + } + + /** + * Returns the number of values equal to v. + * + * @param v the value to lookup. + * @return the frequency of v. + */ + public long getCount(int v) { + return getCount(Long.valueOf(v)); + } + + /** + * Returns the number of values equal to v. + * + * @param v the value to lookup. + * @return the frequency of v. + */ + public long getCount(long v) { + return getCount(Long.valueOf(v)); + } + + /** + * Returns the number of values equal to v. + * + * @param v the value to lookup. + * @return the frequency of v. + */ + public long getCount(char v) { + return getCount(Character.valueOf(v)); + } + + /** + * Returns the number of values in the frequency table. + * + * @return the number of unique values that have been added to the frequency table. + * @see #valuesIterator() + */ + public int getUniqueCount() { + return freqTable.keySet().size(); + } + + /** + * Returns the percentage of values that are equal to v (as a proportion between 0 and 1). + * + * <p>Returns <code>Double.NaN</code> if no values have been added. Returns 0 if at least one + * value has been added, but v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public double getPct(Comparable<?> v) { + final long sumFreq = getSumFreq(); + if (sumFreq == 0) { + return Double.NaN; + } + return (double) getCount(v) / (double) sumFreq; + } + + /** + * Returns the percentage of values that are equal to v (as a proportion between 0 and 1). + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public double getPct(int v) { + return getPct(Long.valueOf(v)); + } + + /** + * Returns the percentage of values that are equal to v (as a proportion between 0 and 1). + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public double getPct(long v) { + return getPct(Long.valueOf(v)); + } + + /** + * Returns the percentage of values that are equal to v (as a proportion between 0 and 1). + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public double getPct(char v) { + return getPct(Character.valueOf(v)); + } + + // ----------------------------------------------------------------------------------------- + + /** + * Returns the cumulative frequency of values less than or equal to v. + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup. + * @return the proportion of values equal to v + */ + @SuppressWarnings({"rawtypes", "unchecked"}) + public long getCumFreq(Comparable<?> v) { + if (getSumFreq() == 0) { + return 0; + } + if (v instanceof Integer) { + return getCumFreq(((Integer) v).longValue()); + } + Comparator<Comparable<?>> c = (Comparator<Comparable<?>>) freqTable.comparator(); + if (c == null) { + c = new NaturalComparator(); + } + long result = 0; + + try { + Long value = freqTable.get(v); + if (value != null) { + result = value.longValue(); + } + } catch (ClassCastException ex) { + return result; // v is not comparable + } + + if (c.compare(v, freqTable.firstKey()) < 0) { + return 0; // v is comparable, but less than first value + } + + if (c.compare(v, freqTable.lastKey()) >= 0) { + return getSumFreq(); // v is comparable, but greater than the last value + } + + Iterator<Comparable<?>> values = valuesIterator(); + while (values.hasNext()) { + Comparable<?> nextValue = values.next(); + if (c.compare(v, nextValue) > 0) { + result += getCount(nextValue); + } else { + return result; + } + } + return result; + } + + /** + * Returns the cumulative frequency of values less than or equal to v. + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public long getCumFreq(int v) { + return getCumFreq(Long.valueOf(v)); + } + + /** + * Returns the cumulative frequency of values less than or equal to v. + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public long getCumFreq(long v) { + return getCumFreq(Long.valueOf(v)); + } + + /** + * Returns the cumulative frequency of values less than or equal to v. + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values equal to v + */ + public long getCumFreq(char v) { + return getCumFreq(Character.valueOf(v)); + } + + // ---------------------------------------------------------------------------------------------- + + /** + * Returns the cumulative percentage of values less than or equal to v (as a proportion between + * 0 and 1). + * + * <p>Returns <code>Double.NaN</code> if no values have been added. Returns 0 if at least one + * value has been added, but v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values less than or equal to v + */ + public double getCumPct(Comparable<?> v) { + final long sumFreq = getSumFreq(); + if (sumFreq == 0) { + return Double.NaN; + } + return (double) getCumFreq(v) / (double) sumFreq; + } + + /** + * Returns the cumulative percentage of values less than or equal to v (as a proportion between + * 0 and 1). + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values less than or equal to v + */ + public double getCumPct(int v) { + return getCumPct(Long.valueOf(v)); + } + + /** + * Returns the cumulative percentage of values less than or equal to v (as a proportion between + * 0 and 1). + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values less than or equal to v + */ + public double getCumPct(long v) { + return getCumPct(Long.valueOf(v)); + } + + /** + * Returns the cumulative percentage of values less than or equal to v (as a proportion between + * 0 and 1). + * + * <p>Returns 0 if v is not comparable to the values set. + * + * @param v the value to lookup + * @return the proportion of values less than or equal to v + */ + public double getCumPct(char v) { + return getCumPct(Character.valueOf(v)); + } + + /** + * Returns the mode value(s) in comparator order. + * + * @return a list containing the value(s) which appear most often. + * @since 3.3 + */ + public List<Comparable<?>> getMode() { + long mostPopular = 0; // frequencies are always positive + + // Get the max count first, so we avoid having to recreate the List each time + for (Long l : freqTable.values()) { + long frequency = l.longValue(); + if (frequency > mostPopular) { + mostPopular = frequency; + } + } + + List<Comparable<?>> modeList = new ArrayList<Comparable<?>>(); + for (Entry<Comparable<?>, Long> ent : freqTable.entrySet()) { + long frequency = ent.getValue().longValue(); + if (frequency == mostPopular) { + modeList.add(ent.getKey()); + } + } + return modeList; + } + + // ---------------------------------------------------------------------------------------------- + + /** + * Merge another Frequency object's counts into this instance. This Frequency's counts will be + * incremented (or set when not already set) by the counts represented by other. + * + * @param other the other {@link Frequency} object to be merged + * @throws NullArgumentException if {@code other} is null + * @since 3.1 + */ + public void merge(final Frequency other) throws NullArgumentException { + MathUtils.checkNotNull(other, LocalizedFormats.NULL_NOT_ALLOWED); + + final Iterator<Map.Entry<Comparable<?>, Long>> iter = other.entrySetIterator(); + while (iter.hasNext()) { + final Map.Entry<Comparable<?>, Long> entry = iter.next(); + incrementValue(entry.getKey(), entry.getValue().longValue()); + } + } + + /** + * Merge a {@link Collection} of {@link Frequency} objects into this instance. This Frequency's + * counts will be incremented (or set when not already set) by the counts represented by each of + * the others. + * + * @param others the other {@link Frequency} objects to be merged + * @throws NullArgumentException if the collection is null + * @since 3.1 + */ + public void merge(final Collection<Frequency> others) throws NullArgumentException { + MathUtils.checkNotNull(others, LocalizedFormats.NULL_NOT_ALLOWED); + + for (final Frequency freq : others) { + merge(freq); + } + } + + // ---------------------------------------------------------------------------------------------- + + /** + * A Comparator that compares comparable objects using the natural order. Copied from Commons + * Collections ComparableComparator. + * + * @param <T> the type of the objects compared + */ + private static class NaturalComparator<T extends Comparable<T>> + implements Comparator<Comparable<T>>, Serializable { + + /** Serializable version identifier */ + private static final long serialVersionUID = -3852193713161395148L; + + /** + * Compare the two {@link Comparable Comparable} arguments. This method is equivalent to: + * + * <pre>(({@link Comparable Comparable})o1).{@link Comparable#compareTo compareTo}(o2)</pre> + * + * @param o1 the first object + * @param o2 the second object + * @return result of comparison + * @throws NullPointerException when <i>o1</i> is <code>null</code>, or when <code> + * ((Comparable)o1).compareTo(o2)</code> does + * @throws ClassCastException when <i>o1</i> is not a {@link Comparable Comparable}, or when + * <code>((Comparable)o1).compareTo(o2)</code> does + */ + @SuppressWarnings("unchecked") // cast to (T) may throw ClassCastException, see Javadoc + public int compare(Comparable<T> o1, Comparable<T> o2) { + return o1.compareTo((T) o2); + } + } + + /** {@inheritDoc} */ + @Override + public int hashCode() { + final int prime = 31; + int result = 1; + result = prime * result + ((freqTable == null) ? 0 : freqTable.hashCode()); + return result; + } + + /** {@inheritDoc} */ + @Override + public boolean equals(Object obj) { + if (this == obj) { + return true; + } + if (!(obj instanceof Frequency)) { + return false; + } + Frequency other = (Frequency) obj; + if (freqTable == null) { + if (other.freqTable != null) { + return false; + } + } else if (!freqTable.equals(other.freqTable)) { + return false; + } + return true; + } +} |