Class LeeDistance
 java.lang.Object

 org.cicirello.permutations.distance.LeeDistance

 All Implemented Interfaces:
NormalizedPermutationDistanceMeasurer
,NormalizedPermutationDistanceMeasurerDouble
,PermutationDistanceMeasurer
,PermutationDistanceMeasurerDouble
public final class LeeDistance extends Object implements NormalizedPermutationDistanceMeasurer
Lee Distance:Lee Distance is closely related to deviation distance. However, Lee Distance considers the permutation to be a cyclic structure when computing positional deviations. That is, an element's deviation between permutations is the minimum of its deviation to the right or to the left (wrapping around ends cyclicly).
Consider p1 = [0, 1, 2, 3, 4, 5] and p2 = [5, 1, 0, 2, 3, 4]. Element 0 is 2 positions displaced (as in deviation distance). Elements 2, 3, and 4 are a 1 position displaced (as in deviation distance). Element 1 is stationary. Element 5 is 1 position displaced (for Lee Distance) whereas for Deviation Distance it would be 5 positions displaced. For Lee distance, the displacement is the minimum of how far it is displaced in either of the two directions. In this case element 5 is at the right most end in p1 and left most end of p2, which as a cyclic structure are adjacent positions.
Runtime: O(n), where n is the permutation length.
Described in:
C. Lee, "Some properties of nonbinary errorcorrecting codes," in IRE Transactions on Information Theory, vol. 4, no. 2, pp. 7782, June 1958.


Constructor Summary
Constructors Constructor Description LeeDistance()
Constructs the distance measurer as specified in the class documentation.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
distance(Permutation p1, Permutation p2)
Measures the distance between two permutations.int
max(int length)
Computes the maximum possible distance between permutations of a specified length.
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.cicirello.permutations.distance.NormalizedPermutationDistanceMeasurer
maxf, normalizedDistance

Methods inherited from interface org.cicirello.permutations.distance.PermutationDistanceMeasurer
distancef




Method Detail

distance
public int distance(Permutation p1, Permutation p2)
Measures the distance between two permutations. Specified by:
distance
in interfacePermutationDistanceMeasurer
 Parameters:
p1
 first permutationp2
 second permutation Returns:
 distance between p1 and p2
 Throws:
IllegalArgumentException
 if p1.length() is not equal to p2.length().

max
public int max(int length)
Description copied from interface:NormalizedPermutationDistanceMeasurer
Computes the maximum possible distance between permutations of a specified length. Specified by:
max
in interfaceNormalizedPermutationDistanceMeasurer
 Parameters:
length
 Permutation length. Returns:
 the maximum distance between a pair of permutations of the specified length.

