home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (Frequency.java)

This example Java source code file (Frequency.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classcastexception, comparable, comparator, frequency, integer, iterator, long, mathillegalargumentexception, nullargumentexception, override, pct, serializable, stringbuilder, suppresswarnings, text, util

The Frequency.java Java example source code

/*
 * 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 java.io.Serializable;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.SortedMap;
import java.util.TreeMap;

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;

/**
 * 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) all have
 * the same effect (similarly for arguments to <code>getCount, 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> * <p> * char values are converted by <code>addValue 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> * 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 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 freqTable; /** * Default constructor. */ public Frequency() { freqTable = new TreeMap<Comparable(); } /** * 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((Comparator>) 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 MathIllegalArgumentException if <code>v 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. * </p> * * @param v the value to add. * @param increment the amount by which the value should be incremented * @throws MathIllegalArgumentException if <code>v 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. * </p> * * @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. * </p> * * @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. * </p> * * @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.</p> * * @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.</p> * * @return entry set Iterator * @since 3.1 */ public Iterator<Map.Entry> 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 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 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 */ @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>) 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 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)); } /** * 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>(); for (Entry<Comparable 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> iter = other.entrySetIterator(); while (iter.hasNext()) { final Map.Entry<Comparable 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 implements Comparator>, 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)
* * @param o1 the first object * @param o2 the second object * @return result of comparison * @throws NullPointerException when <i>o1 is null, * or when <code>((Comparable)o1).compareTo(o2) does * @throws ClassCastException when <i>o1 is not a {@link Comparable Comparable}, * or when <code>((Comparable)o1).compareTo(o2) does */ @SuppressWarnings("unchecked") // cast to (T) may throw ClassCastException, see Javadoc public int compare(Comparable<T> o1, Comparable 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; } }

Other Java examples (source code examples)

Here is a short list of links related to this Java Frequency.java source code file:



my book on functional programming

 

new blog posts

 

Copyright 1998-2019 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.