Changeset 3876 for trunk

Timestamp:

05/31/10 15:58:04 (14 years ago)

Author:

gkronber

Message:

Added support for simplification of average functions and improved simplification of division function. #1026.

File:

• trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SymbolicSimplifier.cs (modified) (4 diffs)

trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SymbolicSimplifier.cs

@@ -67 +67 @@
         // return the correct argument sub-tree (already macro-expanded)
         return (SymbolicExpressionTreeNode)argumentTrees[argSym.ArgumentIndex].Clone();
-      } else if(node.Symbol is StartSymbol) {
+      } else if (node.Symbol is StartSymbol) {
         return MacroExpand(root, subtrees[0], argumentTrees);
       } else {
@@ -136 +136 @@
           return
             MakeMultiplication(simplifiedTrees.First(), Invert(simplifiedTrees.Skip(1).Aggregate((a, b) => MakeMultiplication(a, b))));
+        }
+      } else if (IsAverage(original)) {
+        if (original.SubTrees.Count == 1) {
+          return GetSimplifiedTree(original.SubTrees[0]);
+        } else {
+          // simpliy expressions x0..xn
+          // make sum(x0..xn) / n
+          Trace.Assert(original.SubTrees.Count > 1);
+          var sum = original.SubTrees
+            .Select(x => GetSimplifiedTree(x))
+            .Aggregate((a, b) => MakeAddition(a, b));
+          return MakeDivision(sum, MakeConstant(original.SubTrees.Count));
         }
       } else {
@@ -297 +309 @@
       } else if (IsConstant(b) && IsAddition(a)) {
         return a.SubTrees.Select(x => MakeMultiplication(x, b)).Aggregate((c, d) => MakeAddition(c, d));
+      } else if(IsDivision(a) && IsDivision(b)) {
+        return MakeDivision(MakeMultiplication(a.SubTrees[0], b.SubTrees[0]), MakeMultiplication(a.SubTrees[1], b.SubTrees[1]));
       } else if (IsDivision(a)) {
         Trace.Assert(a.SubTrees.Count == 2);
@@ -351 +365 @@
       return original.Symbol is Constant;
     }
+
+    private bool IsAverage(SymbolicExpressionTreeNode original) {
+      return original.Symbol is Average;
+    }
     #endregion