org.apache.commons.math3.stat

Class Frequency

java.lang.Object

org.apache.commons.math3.stat.Frequency

All Implemented Interfaces:

java.io.Serializable

public class Frequency
extends java.lang.Object
implements java.io.Serializable

Maintains a frequency distribution.

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.

Integer values (int, long, Integer, Long) are not distinguished by type -- i.e. addValue(Long.valueOf(2)), addValue(2), addValue(2l) all have the same effect (similarly for arguments to getCount, etc.).

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.

char values are converted by 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.

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.

The values are ordered using the default (natural order), unless a Comparator is supplied in the constructor.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Frequency.NaturalComparator<T extends java.lang.Comparable<T>> A Comparator that compares comparable objects using the natural order.

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.TreeMap<java.lang.Comparable<?>,java.lang.Long>	freqTable underlying collection
private static long	serialVersionUID Serializable version identifier

Constructor Summary

Constructors

Constructor and Description
Frequency() Default constructor.
Frequency(java.util.Comparator<?> comparator) Constructor allowing values Comparator to be specified.

Method Summary

Methods

Modifier and Type	Method and Description
void	addValue(char v) Adds 1 to the frequency count for v.
void	addValue(java.lang.Comparable<?> v) Adds 1 to the frequency count for v.
void	addValue(int v) Adds 1 to the frequency count for v.
void	addValue(long v) Adds 1 to the frequency count for v.
void	clear() Clears the frequency table
java.util.Iterator<java.util.Map.Entry<java.lang.Comparable<?>,java.lang.Long>>	entrySetIterator() Return an Iterator over the set of keys and values that have been added.
boolean	equals(java.lang.Object obj)
long	getCount(char v) Returns the number of values equal to v.
long	getCount(java.lang.Comparable<?> v) Returns the number of values equal to v.
long	getCount(int v) Returns the number of values equal to v.
long	getCount(long v) Returns the number of values equal to v.
long	getCumFreq(char v) Returns the cumulative frequency of values less than or equal to v.
long	getCumFreq(java.lang.Comparable<?> v) Returns the cumulative frequency of values less than or equal to v.
long	getCumFreq(int v) Returns the cumulative frequency of values less than or equal to v.
long	getCumFreq(long v) Returns the cumulative frequency of values less than or equal to v.
double	getCumPct(char v) Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).
double	getCumPct(java.lang.Comparable<?> v) Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).
double	getCumPct(int v) Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).
double	getCumPct(long v) Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).
java.util.List<java.lang.Comparable<?>>	getMode() Returns the mode value(s) in comparator order.
double	getPct(char v) Returns the percentage of values that are equal to v (as a proportion between 0 and 1).
double	getPct(java.lang.Comparable<?> v) Returns the percentage of values that are equal to v (as a proportion between 0 and 1).
double	getPct(int v) Returns the percentage of values that are equal to v (as a proportion between 0 and 1).
double	getPct(long v) Returns the percentage of values that are equal to v (as a proportion between 0 and 1).
long	getSumFreq() Returns the sum of all frequencies.
int	getUniqueCount() Returns the number of values in the frequency table.
int	hashCode()
void	incrementValue(char v, long increment) Increments the frequency count for v.
void	incrementValue(java.lang.Comparable<?> v, long increment) Increments the frequency count for v.
void	incrementValue(int v, long increment) Increments the frequency count for v.
void	incrementValue(long v, long increment) Increments the frequency count for v.
void	merge(java.util.Collection<Frequency> others) Merge a Collection of Frequency objects into this instance.
void	merge(Frequency other) Merge another Frequency object's counts into this instance.
java.lang.String	toString() Return a string representation of this frequency distribution.
java.util.Iterator<java.lang.Comparable<?>>	valuesIterator() Returns an Iterator over the set of values that have been added.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

Serializable version identifier

See Also:

Constant Field Values

freqTable

private final java.util.TreeMap<java.lang.Comparable<?>,java.lang.Long> freqTable

underlying collection

Constructor Detail

Frequency

public Frequency()

Default constructor.

Frequency

public Frequency(java.util.Comparator<?> comparator)

Constructor allowing values Comparator to be specified.

Parameters:

comparator - Comparator used to order values

Method Detail

toString

public java.lang.String toString()

Return a string representation of this frequency distribution.

Overrides:

toString in class java.lang.Object

Returns:

a string representation.

addValue

public void addValue(java.lang.Comparable<?> v)
              throws MathIllegalArgumentException

Adds 1 to the frequency count for v.

If other objects have already been added to this Frequency, v must be comparable to those that have already been added.

Parameters:

v - the value to add.

Throws:

MathIllegalArgumentException - if v is not comparable with previous entries

addValue

public void addValue(int v)
              throws MathIllegalArgumentException

Adds 1 to the frequency count for v.

Parameters:

v - the value to add.

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Long

addValue

public void addValue(long v)
              throws MathIllegalArgumentException

Adds 1 to the frequency count for v.

Parameters:

v - the value to add.

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Long

addValue

public void addValue(char v)
              throws MathIllegalArgumentException

Adds 1 to the frequency count for v.

Parameters:

v - the value to add.

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Char

incrementValue

public void incrementValue(java.lang.Comparable<?> v,
                  long increment)
                    throws MathIllegalArgumentException

Increments the frequency count for v.

If other objects have already been added to this Frequency, v must be comparable to those that have already been added.

Parameters:

v - the value to add.

increment - the amount by which the value should be incremented

Throws:

MathIllegalArgumentException - if v is not comparable with previous entries

Since:

3.1

incrementValue

public void incrementValue(int v,
                  long increment)
                    throws MathIllegalArgumentException

Increments the frequency count for v.

If other objects have already been added to this Frequency, v must be comparable to those that have already been added.

Parameters:

v - the value to add.

increment - the amount by which the value should be incremented

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Long

Since:

3.3

incrementValue

public void incrementValue(long v,
                  long increment)
                    throws MathIllegalArgumentException

Increments the frequency count for v.

If other objects have already been added to this Frequency, v must be comparable to those that have already been added.

Parameters:

v - the value to add.

increment - the amount by which the value should be incremented

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Long

Since:

3.3

incrementValue

public void incrementValue(char v,
                  long increment)
                    throws MathIllegalArgumentException

Increments the frequency count for v.

If other objects have already been added to this Frequency, v must be comparable to those that have already been added.

Parameters:

v - the value to add.

increment - the amount by which the value should be incremented

Throws:

MathIllegalArgumentException - if the table contains entries not comparable to Char

Since:

3.3

clear

public void clear()

Clears the frequency table

valuesIterator

public java.util.Iterator<java.lang.Comparable<?>> valuesIterator()

Returns an Iterator over the set of values that have been added.

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.

Returns:

values Iterator

entrySetIterator

public java.util.Iterator<java.util.Map.Entry<java.lang.Comparable<?>,java.lang.Long>> entrySetIterator()

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.

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.

Returns:

entry set Iterator

Since:

3.1

getSumFreq

public long getSumFreq()

Returns the sum of all frequencies.

Returns:

the total frequency count.

getCount

public long getCount(java.lang.Comparable<?> v)

Returns the number of values equal to v. Returns 0 if the value is not comparable.

Parameters:

v - the value to lookup.

Returns:

the frequency of v.

getCount

public long getCount(int v)

Returns the number of values equal to v.

Parameters:

v - the value to lookup.

Returns:

the frequency of v.

getCount

public long getCount(long v)

Returns the number of values equal to v.

Parameters:

v - the value to lookup.

Returns:

the frequency of v.

getCount

public long getCount(char v)

Returns the number of values equal to v.

Parameters:

v - the value to lookup.

Returns:

the frequency of v.

getUniqueCount

public int getUniqueCount()

Returns the number of values in the frequency table.

Returns:

the number of unique values that have been added to the frequency table.

See Also:

valuesIterator()

getPct

public double getPct(java.lang.Comparable<?> v)

Returns the percentage of values that are equal to v (as a proportion between 0 and 1).

Returns 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.

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getPct

public double getPct(int v)

Returns the percentage of values that are equal to v (as a proportion between 0 and 1).

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getPct

public double getPct(long v)

Returns the percentage of values that are equal to v (as a proportion between 0 and 1).

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getPct

public double getPct(char v)

Returns the percentage of values that are equal to v (as a proportion between 0 and 1).

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getCumFreq

public long getCumFreq(java.lang.Comparable<?> v)

Returns the cumulative frequency of values less than or equal to v.

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup.

Returns:

the proportion of values equal to v

getCumFreq

public long getCumFreq(int v)

Returns the cumulative frequency of values less than or equal to v.

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getCumFreq

public long getCumFreq(long v)

Returns the cumulative frequency of values less than or equal to v.

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getCumFreq

public long getCumFreq(char v)

Returns the cumulative frequency of values less than or equal to v.

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values equal to v

getCumPct

public double getCumPct(java.lang.Comparable<?> v)

Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).

Returns 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.

Parameters:

v - the value to lookup

Returns:

the proportion of values less than or equal to v

getCumPct

public double getCumPct(int v)

Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values less than or equal to v

getCumPct

public double getCumPct(long v)

Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values less than or equal to v

getCumPct

public double getCumPct(char v)

Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).

Returns 0 if v is not comparable to the values set.

Parameters:

v - the value to lookup

Returns:

the proportion of values less than or equal to v

getMode

public java.util.List<java.lang.Comparable<?>> getMode()

Returns the mode value(s) in comparator order.

Returns:

a list containing the value(s) which appear most often.

Since:

3.3

merge

public void merge(Frequency other)
           throws NullArgumentException

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.

Parameters:

other - the other Frequency object to be merged

Throws:

NullArgumentException - if other is null

Since:

3.1

merge

public void merge(java.util.Collection<Frequency> others)
           throws NullArgumentException

Merge a Collection of 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.

Parameters:

others - the other Frequency objects to be merged

Throws:

NullArgumentException - if the collection is null

Since:

3.1

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object