/*
* 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.math.stat;
import java.io.Serializable;
import java.text.NumberFormat;
import java.util.Iterator;
import java.util.Comparator;
import java.util.TreeMap;
import org.apache.commons.math.MathRuntimeException;
import org.apache.commons.math.exception.util.LocalizedFormats;
/**
* 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>
* <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>
* <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>
* <p>
* The values are ordered using the default (natural order), unless a
* <code>Comparator</code> is supplied in the constructor.</p>
*
* @version $Id: Frequency.java 1131229 2011-06-03 20:49:25Z luc $
*/
public class Frequency implements Serializable {
/** Serializable version identifier */
private static final long serialVersionUID = -3845586908418844111L;
/** underlying collection */
private final TreeMap<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.
* </p>
*
* @param v the value to add.
* @throws IllegalArgumentException if <code>v</code> is not comparable with previous entries
*/
public void addValue(Comparable<?> v){
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(1));
} else {
freqTable.put(obj, Long.valueOf(count.longValue() + 1));
}
} catch (ClassCastException ex) {
//TreeMap will throw ClassCastException if v is not comparable
throw MathRuntimeException.createIllegalArgumentException(
LocalizedFormats.INSTANCES_NOT_COMPARABLE_TO_EXISTING_VALUES,
v.getClass().getName());
}
}
/**
* Adds 1 to the frequency count for v.
*
* @param v the value to add.
*/
public void addValue(int v) {
addValue(Long.valueOf(v));
}
/**
* Adds 1 to the frequency count for v.
*
* @param v the value to add.
*/
public void addValue(long v) {
addValue(Long.valueOf(v));
}
/**
* Adds 1 to the frequency count for v.
*
* @param v the value to add.
*/
public void addValue(char v) {
addValue(Character.valueOf(v));
}
/** 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.</p>
*
* @return values Iterator
*/
public Iterator<Comparable<?>> valuesIterator() {
return freqTable.keySet().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 = 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) {
// ignore and return 0 -- ClassCastException will be thrown if value is not comparable
}
return result;
}
/**
* Returns the number of values = 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 = 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 = 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.</p>
*
* @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.</p>
*
* @param v the value to lookup.
* @return the proportion of values equal to v
*/
public long getCumFreq(Comparable<?> v) {
if (getSumFreq() == 0) {
return 0;
}
if (v instanceof Integer) {
return getCumFreq(((Integer) v).longValue());
}
@SuppressWarnings("unchecked") // OK, freqTable is Comparable<?>
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.</p>
*
* @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.</p>
*
* @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.</p>
*
* @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.</p>
*
* @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.</p>
*
* @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.</p>
*
* @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.</p>
*
* @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));
}
/**
* A Comparator that compares comparable objects using the
* natural order. Copied from Commons Collections ComparableComparator.
*/
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;
}
}