Combinations.LexicographicComparator

java.lang.Object

org.apache.commons.math3.util.Combinations.LexicographicComparator

All Implemented Interfaces:: Serializable, Comparator<int[]>

Enclosing class:: Combinations

private static class Combinations.LexicographicComparator extends Object implements Comparator<int[]>, Serializable

Defines the lexicographic ordering of combinations, using the lexNorm(int[]) method.

Field Summary

Fields

Modifier and Type

Field

Description

private final int

k

Number of elements in each combination.

private final int

n

Size of the set from which combinations are drawn.

private static final long

serialVersionUID

Serializable version identifier.
Constructor Summary

Constructors

Constructor

Description

LexicographicComparator(int n, int k)
Method Summary

Modifier and Type

Method

Description

int

compare(int[] c1, int[] c2)

private long

lexNorm(int[] c)

Computes the value (in base 10) represented by the digit (interpreted in base n) in the input array in reverse order.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator
equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Details
- serialVersionUID
  
  private static final long serialVersionUID
  
  Serializable version identifier.
  See Also:
  
  Constant Field Values
- n
  
  private final int n
  
  Size of the set from which combinations are drawn.
- k
  
  private final int k
  
  Number of elements in each combination.
Constructor Details
- LexicographicComparator
  
  LexicographicComparator(int n, int k)
  
  Parameters:
  
  n - Size of the set from which subsets are selected.
  
  k - Size of the subsets to be enumerated.
Method Details
- compare
  
  public int compare(int[] c1, int[] c2)
  
  Specified by:
  
  compare in interface Comparator<int[]>
  
  Throws:
  
  DimensionMismatchException - if the array lengths are not equal to k.
  
  OutOfRangeException - if an element of the array is not within the interval [0, n).
- lexNorm
  
  private long lexNorm(int[] c)
  
  Computes the value (in base 10) represented by the digit (interpreted in base n) in the input array in reverse order. For example if c is {3, 2, 1}, and n is 3, the method will return 18.
  
  Parameters:
  
  c - Input array.
  
  Returns:
  
  the lexicographic norm.
  
  Throws:
  
  OutOfRangeException - if an element of the array is not within the interval [0, n).