Package org.apache.commons.math3.stat

Class Frequency

java.lang.Object
org.apache.commons.math3.stat.Frequency
All Implemented Interfaces:
Serializable
public class Frequency extends Object implements 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:

  • Constructor Summary

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

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addValue(char 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
    addValue(Comparable<?> v)
    Adds 1 to the frequency count for v.
    void
    clear()
    Clears the frequency table
    Iterator<Map.Entry<Comparable<?>,Long>>
    entrySetIterator()
    Return an Iterator over the set of keys and values that have been added.
    boolean
    equals(Object obj)
    long
    getCount(char 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
    getCount(Comparable<?> 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(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.
    long
    getCumFreq(Comparable<?> 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(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).
    double
    getCumPct(Comparable<?> v)
    Returns the cumulative percentage of values less than or equal to v (as a proportion between 0 and 1).
    List<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(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).
    double
    getPct(Comparable<?> 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(int v, long increment)
    Increments the frequency count for v.
    void
    incrementValue(long v, long increment)
    Increments the frequency count for v.
    void
    incrementValue(Comparable<?> v, long increment)
    Increments the frequency count for v.
    void
    merge(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.
    String
    toString()
    Return a string representation of this frequency distribution.
    Iterator<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

  • Constructor Details

    • Frequency

      public Frequency()
      Default constructor.

    • Frequency

      public Frequency(Comparator<?> comparator)
      Constructor allowing values Comparator to be specified.
      Parameters:
      comparator - Comparator used to order values

  • Method Details

    • toString

      public String toString()
      Return a string representation of this frequency distribution.
      Overrides:
      toString in class Object
      Returns:
      a string representation.

    • addValue

      public void addValue(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(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 Iterator<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 Iterator<Map.Entry<Comparable<?>,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(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:

    • getPct

      public double getPct(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(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(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 List<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(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 Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object