org.matheclipse.combinatoric.util

Class ArrayUtils

java.lang.Object

org.matheclipse.combinatoric.util.ArrayUtils

public final class ArrayUtils
extends java.lang.Object

Provides a couple of static utility methods for creating and initializing arrays used throughout permutation and combination generation.

Method Summary

Modifier and Type	Method and Description
static int[]	deleteSubset(int[] multiset, int[] subset) Iterate over the elements in the subset and set the first elements to -1 in the multiset which equals the subset elements.
static int[]	identityPermutation(int n) Creates and fills an array with a[i] = i.
static void	identityPermutation(int[] a) Fills the given array with a[i] = i.
static char[]	valuesAt(char[] elements, int[] indices)
static int[]	valuesAt(int[] elements, int[] indices)
static <T> T[]	valuesAt(T[] elements, int[] indices)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

deleteSubset

public static int[] deleteSubset(int[] multiset,
                                 int[] subset)

Iterate over the elements in the subset and set the first elements to -1 in the multiset which equals the subset elements. Return a new reduced multiset int[] array where the -1 values are deleted.

Parameters:

multiset - a multiset containing equals or greater than elements as the subset.

subset - a subset with the elements which should be deleted.

Returns:

identityPermutation

public static void identityPermutation(int[] a)

Fills the given array with a[i] = i. For example, if a = int[4], then fills a with { 0, 1, 2, 3 }. Used throughout permutation and combination generation as the first result (lexicographically).

Parameters:

a - an array

identityPermutation

public static int[] identityPermutation(int n)

Creates and fills an array with a[i] = i. For example, if n = 4, then returns { 0, 1, 2, 3 }. Used throughout permutation and combination generation as the first result (lexicographically).

Parameters:

n - the size of the array

Returns:

the initialized array

valuesAt

public static char[] valuesAt(char[] elements,
                              int[] indices)

Parameters:

elements - the elements to choose from

indices - the array of indices

Returns:

the mapped array

valuesAt

public static int[] valuesAt(int[] elements,
                             int[] indices)

Parameters:

elements - the elements to choose from

indices - the array of indices

Returns:

the mapped array

valuesAt

public static <T> T[] valuesAt(T[] elements,
                               int[] indices)

Type Parameters:

T - a type

Parameters:

elements - the elements to choose from

indices - the array of indices

Returns:

the mapped array