Class CyclicReversalIndependentDistanceDouble
- java.lang.Object
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- org.cicirello.permutations.distance.CyclicReversalIndependentDistanceDouble
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- All Implemented Interfaces:
PermutationDistanceMeasurerDouble
public final class CyclicReversalIndependentDistanceDouble extends Object implements PermutationDistanceMeasurerDouble
This class implements the combination of cyclic independence and reversal independence. This is relevant if any rotation of the permutation or its reverse has the same problem dependent interpretation. For example, if the permutation represents a solution to a traveling salesperson problem (i.e. a tour of a set of cities), then the cost of that tour is the same if you rotate it, reverse it, or reverse it and rotate it.
In this case, this class computes the minimum of the distance from permutation p1 to rotations of p2 and rotations of the reverse of p2, where the underlying distance measure is passed as a parameter to the constructor.
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Constructor Summary
Constructors Constructor Description CyclicReversalIndependentDistanceDouble(PermutationDistanceMeasurerDouble d)
Constructs a distance measure for measuring distance with cyclic and reversal independence, such that distance = min_{i in [0,N)} { distance(p1,rotate(p2,i)), distance(p1,rotate(reverse(p2),i)) }
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description double
distancef(Permutation p1, Permutation p2)
Measures the distance between two permutations, with cyclic and reversal independence: distance = min_{i in [0,N)} { distance(p1,rotate(p2,i)), distance(p1,rotate(reverse(p2),i)) }
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Constructor Detail
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CyclicReversalIndependentDistanceDouble
public CyclicReversalIndependentDistanceDouble(PermutationDistanceMeasurerDouble d)
Constructs a distance measure for measuring distance with cyclic and reversal independence, such that distance = min_{i in [0,N)} { distance(p1,rotate(p2,i)), distance(p1,rotate(reverse(p2),i)) }- Parameters:
d
- A distance measure.
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Method Detail
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distancef
public double distancef(Permutation p1, Permutation p2)
Measures the distance between two permutations, with cyclic and reversal independence: distance = min_{i in [0,N)} { distance(p1,rotate(p2,i)), distance(p1,rotate(reverse(p2),i)) }- Specified by:
distancef
in interfacePermutationDistanceMeasurerDouble
- Parameters:
p1
- first permutationp2
- second permutation- Returns:
- distance between p1 and p2
- Throws:
IllegalArgumentException
- if p1.length() is not equal to p2.length().
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