commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/Frequency.java - commons-math - Git at Google

 /*
  * 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.math4.legacy.stat;

 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;

 import org.apache.commons.math4.legacy.exception.NullArgumentException;
 import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;

 /**
  * Maintains a frequency distribution.
  *
  * <p>The values are ordered using the default (natural order), unless a
  * <code>Comparator</code> is supplied in the constructor.</p>
  *
  * @param <T> a comparable type used in the frequency distribution
  */
 public class Frequency<T extends Comparable<T>> {
     /** underlying collection. */
     private final SortedMap<T, Long> freqTable;

     /**
      * Default constructor.
      */
     public Frequency() {
         freqTable = new TreeMap<>();
     }

     /**
      * Constructor allowing values Comparator to be specified.
      *
      * @param comparator Comparator used to order values
      */
     public Frequency(Comparator<T> comparator) {
         freqTable = new TreeMap<>(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<T> iter = freqTable.keySet().iterator();
         while (iter.hasNext()) {
             T 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.
      *
      * @param v the value to add.
      */
     public void addValue(T v) {
         incrementValue(v, 1);
     }

     /**
      * Increments the frequency count for v.
      *
      * @param v the value to add.
      * @param increment the amount by which the value should be incremented
      * @since 3.1
      */
     public void incrementValue(T v, long increment) {
         Long count = freqTable.get(v);
         if (count == null) {
             freqTable.put(v, Long.valueOf(increment));
         } else {
             freqTable.put(v, Long.valueOf(count.longValue() + increment));
         }
     }

     /** Clears the frequency table. */
     public void clear() {
         freqTable.clear();
     }

     /**
      * Returns an Iterator over the set of values that have been added.
      *
      * @return values Iterator
      */
     public Iterator<T> 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.
      *
      * @return entry set Iterator
      * @since 3.1
      */
     public Iterator<Map.Entry<T, 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.
      *
      * @param v the value to lookup.
      * @return the frequency of v.
      */
     public long getCount(T v) {
         long result = 0;
         Long count =  freqTable.get(v);
         if (count != null) {
             result = count.longValue();
         }
         return result;
     }

     /**
      * 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(T v) {
         final long sumFreq = getSumFreq();
         if (sumFreq == 0) {
             return Double.NaN;
         }
         return (double) getCount(v) / (double) sumFreq;
     }

     //-----------------------------------------------------------------------------------------

     /**
      * Returns the cumulative frequency of values less than or equal to v.
      *
      * @param v the value to lookup.
      * @return the proportion of values equal to v
      */
     public long getCumFreq(T v) {
         if (getSumFreq() == 0) {
             return 0;
         }
         Comparator<? super T> c = freqTable.comparator();
         if (c == null) {
             c = new NaturalComparator<T>();
         }
         long result = 0;

         Long value = freqTable.get(v);
         if (value != null) {
             result = value.longValue();
         }

         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<T> values = valuesIterator();
         while (values.hasNext()) {
             T nextValue = values.next();
             if (c.compare(v, nextValue) > 0) {
                 result += getCount(nextValue);
             } else {
                 return result;
             }
         }
         return result;
     }

     //----------------------------------------------------------------------------------------------

     /**
      * 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.
      * </p>
      *
      * @param v the value to lookup
      * @return the proportion of values less than or equal to v
      */
     public double getCumPct(T v) {
         final long sumFreq = getSumFreq();
         if (sumFreq == 0) {
             return Double.NaN;
         }
         return (double) getCumFreq(v) / (double) sumFreq;
     }

     /**
      * Returns the mode value(s) in comparator order.
      *
      * @return a list containing the value(s) which appear most often.
      * @since 3.3
      */
     public List<T> 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<T> modeList = new ArrayList<>();
         for (Entry<T, 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<T> other) throws NullArgumentException {
         NullArgumentException.check(other, LocalizedFormats.NULL_NOT_ALLOWED);

         final Iterator<Map.Entry<T, Long>> iter = other.entrySetIterator();
         while (iter.hasNext()) {
             final Map.Entry<T, 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<T>> others) throws NullArgumentException {
         NullArgumentException.check(others, LocalizedFormats.NULL_NOT_ALLOWED);

         for (final Frequency<T> freq : others) {
             merge(freq);
         }
     }

     //----------------------------------------------------------------------------------------------

     /**
      * A Comparator that compares comparable objects using the
      * natural order. Copied from Commons Collections ComparableComparator.
      *
      * @param <U> the type of the objects compared
      */
     private static class NaturalComparator<U extends Comparable<U>> implements Comparator<U> {
         /**
          * 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
          */
         @Override
         public int compare(U o1, U o2) {
             return o1.compareTo(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;
         return freqTable.equals(other.freqTable);
     }

 }
	/*
	* 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.math4.legacy.stat;

	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;

	import org.apache.commons.math4.legacy.exception.NullArgumentException;
	import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;

	/**
	* Maintains a frequency distribution.
	*
	* <p>The values are ordered using the default (natural order), unless a
	* <code>Comparator</code> is supplied in the constructor.</p>
	*
	* @param <T> a comparable type used in the frequency distribution
	*/
	public class Frequency<T extends Comparable<T>> {
	/** underlying collection. */
	private final SortedMap<T, Long> freqTable;

	/**
	* Default constructor.
	*/
	public Frequency() {
	freqTable = new TreeMap<>();
	}

	/**
	* Constructor allowing values Comparator to be specified.
	*
	* @param comparator Comparator used to order values
	*/
	public Frequency(Comparator<T> comparator) {
	freqTable = new TreeMap<>(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<T> iter = freqTable.keySet().iterator();
	while (iter.hasNext()) {
	T 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.
	*
	* @param v the value to add.
	*/
	public void addValue(T v) {
	incrementValue(v, 1);
	}

	/**
	* Increments the frequency count for v.
	*
	* @param v the value to add.
	* @param increment the amount by which the value should be incremented
	* @since 3.1
	*/
	public void incrementValue(T v, long increment) {
	Long count = freqTable.get(v);
	if (count == null) {
	freqTable.put(v, Long.valueOf(increment));
	} else {
	freqTable.put(v, Long.valueOf(count.longValue() + increment));
	}
	}

	/** Clears the frequency table. */
	public void clear() {
	freqTable.clear();
	}

	/**
	* Returns an Iterator over the set of values that have been added.
	*
	* @return values Iterator
	*/
	public Iterator<T> 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.
	*
	* @return entry set Iterator
	* @since 3.1
	*/
	public Iterator<Map.Entry<T, 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.
	*
	* @param v the value to lookup.
	* @return the frequency of v.
	*/
	public long getCount(T v) {
	long result = 0;
	Long count = freqTable.get(v);
	if (count != null) {
	result = count.longValue();
	}
	return result;
	}

	/**
	* 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(T v) {
	final long sumFreq = getSumFreq();
	if (sumFreq == 0) {
	return Double.NaN;
	}
	return (double) getCount(v) / (double) sumFreq;
	}

	//-----------------------------------------------------------------------------------------

	/**
	* Returns the cumulative frequency of values less than or equal to v.
	*
	* @param v the value to lookup.
	* @return the proportion of values equal to v
	*/
	public long getCumFreq(T v) {
	if (getSumFreq() == 0) {
	return 0;
	}
	Comparator<? super T> c = freqTable.comparator();
	if (c == null) {
	c = new NaturalComparator<T>();
	}
	long result = 0;

	Long value = freqTable.get(v);
	if (value != null) {
	result = value.longValue();
	}

	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<T> values = valuesIterator();
	while (values.hasNext()) {
	T nextValue = values.next();
	if (c.compare(v, nextValue) > 0) {
	result += getCount(nextValue);
	} else {
	return result;
	}
	}
	return result;
	}

	//----------------------------------------------------------------------------------------------

	/**
	* 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.
	* </p>
	*
	* @param v the value to lookup
	* @return the proportion of values less than or equal to v
	*/
	public double getCumPct(T v) {
	final long sumFreq = getSumFreq();
	if (sumFreq == 0) {
	return Double.NaN;
	}
	return (double) getCumFreq(v) / (double) sumFreq;
	}

	/**
	* Returns the mode value(s) in comparator order.
	*
	* @return a list containing the value(s) which appear most often.
	* @since 3.3
	*/
	public List<T> 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<T> modeList = new ArrayList<>();
	for (Entry<T, 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<T> other) throws NullArgumentException {
	NullArgumentException.check(other, LocalizedFormats.NULL_NOT_ALLOWED);

	final Iterator<Map.Entry<T, Long>> iter = other.entrySetIterator();
	while (iter.hasNext()) {
	final Map.Entry<T, 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<T>> others) throws NullArgumentException {
	NullArgumentException.check(others, LocalizedFormats.NULL_NOT_ALLOWED);

	for (final Frequency<T> freq : others) {
	merge(freq);
	}
	}

	//----------------------------------------------------------------------------------------------

	/**
	* A Comparator that compares comparable objects using the
	* natural order. Copied from Commons Collections ComparableComparator.
	*
	* @param <U> the type of the objects compared
	*/
	private static class NaturalComparator<U extends Comparable<U>> implements Comparator<U> {
	/**
	* 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
	*/
	@Override
	public int compare(U o1, U o2) {
	return o1.compareTo(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;
	return freqTable.equals(other.freqTable);
	}

	}