org.apache.commons.math3.util

Class Combinations.LexicographicComparator

java.lang.Object

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

All Implemented Interfaces:

java.io.Serializable, java.util.Comparator<int[]>

Enclosing class:

Combinations

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

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

Field Summary

Fields

Modifier and Type	Field and Description
private int	k Number of elements in each combination.
private int	n Size of the set from which combinations are drawn.
private static long	serialVersionUID Serializable version identifier.

Constructor Summary

Constructors

Constructor and Description
Combinations.LexicographicComparator(int n, int k)

Method Summary

Methods

Modifier and Type	Method and 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

Field Detail

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 Detail

Combinations.LexicographicComparator

public Combinations.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 Detail

compare

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

Specified by:

compare in interface java.util.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).