Changeset 3706 for trunk/sources/HeuristicLab.Encodings.PermutationEncoding/3.3/Moves/TwoOpt

Timestamp:

05/07/10 16:29:25 (15 years ago)

Author:

abeham

Message:

#839

• Added some checks to allow moves in permutation of length 2 or 3.

Location:

trunk/sources/HeuristicLab.Encodings.PermutationEncoding/3.3/Moves/TwoOpt

Files:

• ExhaustiveInversionMoveGenerator.cs (modified) (2 diffs)
• StochasticInversionSingleMoveGenerator.cs (modified) (1 diff)

trunk/sources/HeuristicLab.Encodings.PermutationEncoding/3.3/Moves/TwoOpt/ExhaustiveInversionMoveGenerator.cs

@@ -32 +32 @@
     public static InversionMove[] Apply(Permutation permutation) {
       int length = permutation.Length;
+      if (length == 1) throw new ArgumentException("ExhaustiveInversionMoveGenerator: There cannot be an inversion move given a permutation of length 1.", "permutation");
       int totalMoves = (length) * (length - 1) / 2;
       InversionMove[] moves = null;
@@ -37 +38 @@
 
       if (permutation.PermutationType == PermutationTypes.RelativeUndirected) {
-        moves = new InversionMove[totalMoves - 3];
-        for (int i = 0; i < length - 1; i++) {
-          for (int j = i + 1; j < length; j++) {
-            // doesn't make sense to inverse the whole permutation or the whole but one in case of relative undirected permutations
-            if (j - i >= length - 2) continue;
-            moves[count++] = new InversionMove(i, j);
+        if (totalMoves - 3 > 0) {
+          moves = new InversionMove[totalMoves - 3];
+          for (int i = 0; i < length - 1; i++) {
+            for (int j = i + 1; j < length; j++) {
+              // doesn't make sense to inverse the whole permutation or the whole but one in case of relative undirected permutations
+              if (j - i >= length - 2) continue;
+              moves[count++] = new InversionMove(i, j);
+            }
           }
+        } else { // when length is 3 or less, there's actually no difference, but for the sake of not crashing the algorithm create a dummy move
+          moves = new InversionMove[1];
+          moves[0] = new InversionMove(0, 1);
         }
       } else {

trunk/sources/HeuristicLab.Encodings.PermutationEncoding/3.3/Moves/TwoOpt/StochasticInversionSingleMoveGenerator.cs

@@ -43 +43 @@
     public static InversionMove Apply(Permutation permutation, IRandom random) {
       int length = permutation.Length;
+      if (length == 1) throw new ArgumentException("StochasticInversionSingleMoveGenerator: There cannot be an inversion move given a permutation of length 1.", "permutation");
       int index1 = random.Next(length - 1);
       int index2 = random.Next(index1 + 1, length);
       if (permutation.PermutationType == PermutationTypes.RelativeUndirected) {
-        while (index2 - index1 >= length - 2)
-          index2 = random.Next(index1 + 1, length);
+        if (length > 3) {
+          while (index2 - index1 >= length - 2)
+            index2 = random.Next(index1 + 1, length);
+        }
       }
       return new InversionMove(index1, index2);