Struct Permutation
- Namespace
- Evolutionary
- Assembly
- Evolutionary.dll
Represents a permutation of the numbers 0 to n-1. The permutation is an immutable individual for permutation-based evolutionary algorithms.
public readonly struct Permutation : IEquatable<Permutation>, IReadOnlyList<int>, IReadOnlyCollection<int>, IEnumerable<int>, IEnumerable- Implements
- Inherited Members
Remarks
A permutation can either be linear or circular. A circular permutation treats the first and the last element as adjacent. The default instance of the struct is an empty linear permutation.
Constructors
Permutation(int)
Initializes a new linear permutation of the numbers 0 to
n-1.
public Permutation(int n)Parameters
nintThe number of elements.
Permutation(int, bool)
Initializes a new permutation of the numbers 0 to
n-1.
public Permutation(int n, bool isCircular)Parameters
Permutation(int[], bool)
Initializes a new permutation from the given array. The array is not copied and not validated.
public Permutation(int[] array, bool isCircular)Parameters
arrayint[]The elements of the permutation.
isCircularboolIndicates whether the permutation is circular.
Properties
Count
Gets the number of elements.
public int Count { get; }Property Value
IsCircular
Gets a value indicating whether the permutation is circular.
public bool IsCircular { get; }Property Value
this[int]
Gets the element at the given index.
public int this[int index] { get; }Parameters
indexintThe zero-based index of the element.
Property Value
- int
The element.
Methods
CreateCircularRandomly(int, Random)
Creates a new circular permutation whose elements are shuffled randomly. The first element is always 0, as the circular permutation has no well-defined first element.
public static Permutation CreateCircularRandomly(int n, Random random)Parameters
Returns
- Permutation
The random circular permutation.
CreateRandomly(int, Random)
Creates a new linear permutation whose elements are shuffled randomly.
public static Permutation CreateRandomly(int n, Random random)Parameters
Returns
- Permutation
The random permutation.
CutAndCrossfillCrossover(Permutation, Permutation, int)
Creates a child by a cut and crossfill crossover. The prefix of the first parent is copied into the child, and the child is completed by the remaining elements of the second parent in their original order.
public static Permutation CutAndCrossfillCrossover(Permutation p1, Permutation p2, int position)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
positionintThe number of elements that are copied from the first parent.
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
- InvalidOperationException
Thrown if the permutation is too short for this operation.
- ArgumentOutOfRangeException
Thrown if the position is out of the valid range.
CutAndCrossfillCrossover(Permutation, Permutation, Random)
Creates a child by a cut and crossfill crossover. The prefix of the first parent is copied into the child, and the child is completed by the remaining elements of the second parent in their original order.
public static Permutation CutAndCrossfillCrossover(Permutation p1, Permutation p2, Random random)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
randomRandomThe random number generator.
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
- InvalidOperationException
Thrown if the permutation is too short for this operation.
CycleCrossover(Permutation, Permutation)
Creates a child by a cycle crossover (CX). The elements at cycle positions are taken from the first parent and the others from the second parent.
public static Permutation CycleCrossover(Permutation p1, Permutation p2)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
CycleCrossover(Permutation, Permutation, Random)
Creates a child by a cycle crossover (CX). The random number generator is not used; the overload exists for API consistency with the other recombination operators.
public static Permutation CycleCrossover(Permutation p1, Permutation p2, Random random)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
randomRandomThe random number generator (unused).
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
Equals(Permutation)
Indicates whether the current permutation and the given one are equal. Two permutations are equal if they have the same circularity and the same sequence of elements.
public bool Equals(Permutation other)Parameters
otherPermutationThe other permutation.
Returns
Equals(object?)
Indicates whether the current permutation and the given object are equal.
public override bool Equals(object? obj)Parameters
objobjectThe object to compare with.
Returns
GetEnumerator()
Returns an enumerator that iterates through the elements.
public IEnumerator<int> GetEnumerator()Returns
- IEnumerator<int>
The enumerator.
GetHashCode()
Returns a hash code for the permutation. Two equal permutations have the same hash code.
public override int GetHashCode()Returns
- int
The hash code.
InsertMutation(Permutation, Random)
Removes a randomly selected element and reinserts it at another randomly selected position. The elements in between are shifted (insertion mutation).
public static Permutation InsertMutation(Permutation permutation, Random random)Parameters
permutationPermutationThe permutation to mutate.
randomRandomThe random number generator.
Returns
- Permutation
The mutated permutation.
Exceptions
- InvalidOperationException
Thrown if the permutation is too short for this operation.
InversionMutation(Permutation, Random)
Reverses the elements between two randomly selected positions (inversion mutation).
public static Permutation InversionMutation(Permutation permutation, Random random)Parameters
permutationPermutationThe permutation to mutate.
randomRandomThe random number generator.
Returns
- Permutation
The mutated permutation.
Exceptions
- InvalidOperationException
Thrown if the permutation is too short for this operation.
PartiallyMappedCrossover(Permutation, Permutation, int, int)
Creates a child by a partially mapped crossover (PMX). The selected segment of the first parent is copied into the child, and the remaining elements are taken from the second parent, with duplicates being resolved by the partial mapping.
public static Permutation PartiallyMappedCrossover(Permutation p1, Permutation p2, int start, int length)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
startintThe start position of the mapped segment.
lengthintThe length of the mapped segment.
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
- InvalidOperationException
Thrown if the permutation is too short for this operation.
- ArgumentOutOfRangeException
Thrown if the start position or the length is out of the valid range.
PartiallyMappedCrossover(Permutation, Permutation, Random)
Creates a child by a partially mapped crossover (PMX). A randomly selected segment of the first parent is copied into the child, and the remaining elements are taken from the second parent, with duplicates being resolved by the partial mapping.
public static Permutation PartiallyMappedCrossover(Permutation p1, Permutation p2, Random random)Parameters
p1PermutationThe first parent.
p2PermutationThe second parent.
randomRandomThe random number generator.
Returns
- Permutation
The child.
Exceptions
- ArgumentException
Thrown if the element counts or the circularity of both permutations differ.
- InvalidOperationException
Thrown if the permutation is too short for this operation.
ScrambleMutation(Permutation, Random)
Randomly shuffles the elements between two randomly selected positions (scramble mutation).
public static Permutation ScrambleMutation(Permutation permutation, Random random)Parameters
permutationPermutationThe permutation to mutate.
randomRandomThe random number generator.
Returns
- Permutation
The mutated permutation.
Exceptions
- InvalidOperationException
Thrown if the permutation is too short for this operation.
SwapMutation(Permutation, Random)
Swaps the elements at two randomly selected positions (swap mutation).
public static Permutation SwapMutation(Permutation permutation, Random random)Parameters
permutationPermutationThe permutation to mutate.
randomRandomThe random number generator.
Returns
- Permutation
The mutated permutation.
Exceptions
- InvalidOperationException
Thrown if the permutation is too short for this operation.
ToArray()
Returns a copy of the permutation as array.
public int[] ToArray()Returns
- int[]
The elements of the permutation.
Operators
operator ==(Permutation, Permutation)
Indicates whether two permutations are equal.
public static bool operator ==(Permutation lhs, Permutation rhs)Parameters
lhsPermutationThe first permutation.
rhsPermutationThe second permutation.
Returns
implicit operator ReadOnlySpan<int>(Permutation)
Converts the permutation into a read-only span of its elements.
public static implicit operator ReadOnlySpan<int>(Permutation permutation)Parameters
permutationPermutationThe permutation.
Returns
operator !=(Permutation, Permutation)
Indicates whether two permutations are not equal.
public static bool operator !=(Permutation lhs, Permutation rhs)Parameters
lhsPermutationThe first permutation.
rhsPermutationThe second permutation.