Changeset 17596

Timestamp:

06/10/20 13:47:08 (4 years ago)

Author:

pfleck

Message:

#3040: added subtraction/division simplification for sum and mean symbols by converting them to sums/products.

File:

• branches/3040_VectorBasedGP/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/VectorTreeSimplifier.cs (modified) (4 diffs)

branches/3040_VectorBasedGP/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/VectorTreeSimplifier.cs

@@ -1370 +1370 @@
       if (IsConstant(node)) { // assumes scalar constant
         return node;
-      } else if (IsAddition(node)) {
+      } else if (IsAddition(node) || IsSubtraction(node)) {
         var terms = node.Subtrees;
+        if (IsSubtraction(node)) {
+          if (terms.Count() == 1) {
+            terms = terms.Select(Negate);
+          } else {
+            var first = terms.First().ToEnumerable();
+            var remaining = terms.Skip(1).Select(Negate);
+            terms = first.Concat(remaining).ToList();
+          }
+        }
+
         var scalarTerms = terms.Where(IsScalarNode).ToList();
         var remainingTerms = terms.Except(scalarTerms).ToList();
@@ -1399 +1409 @@
         } else
           throw new InvalidOperationException("Addition does not contain any terms to simplify.");
-      } else if (IsMultiplication(node)) {
+      } else if (IsMultiplication(node) || IsDivision(node)) {
         var factors = node.Subtrees;
+        if (IsDivision(node)) {
+          if (factors.Count() == 1) {
+            factors = factors.Select(Invert);
+          } else {
+            var first = factors.First().ToEnumerable();
+            var remaining = factors.Skip(1).Select(Invert);
+            factors = first.Concat(remaining).ToList();
+          }
+        }
+
         var scalarFactors = factors.Where(IsScalarNode).ToList();
         var remainingFactors = factors.Except(scalarFactors).ToList();
@@ -1432 +1452 @@
       if (IsConstant(node)) { // assumes scalar constant
         return node;
-      } else if (IsAddition(node)) {
+      } else if (IsAddition(node) || IsSubtraction(node)) {
         var terms = node.Subtrees;
+        if (IsSubtraction(node)) {
+          if (terms.Count() == 1) {
+            terms = terms.Select(Negate);
+          } else {
+            var first = terms.First().ToEnumerable();
+            var remaining = terms.Skip(1).Select(Negate);
+            terms = first.Concat(remaining).ToList();
+          }
+        }
+
         var scalarTerms = terms.Where(IsScalarNode).ToList();
         var remainingTerms = terms.Except(scalarTerms).ToList();
@@ -1455 +1485 @@
         } else
           throw new InvalidOperationException("Addition does not contain any terms to simplify.");
-      } else if (IsMultiplication(node)) {
+      } else if (IsMultiplication(node) || IsDivision(node)) {
         var factors = node.Subtrees;
+        if (IsDivision(node)) {
+          if (factors.Count() == 1) {
+            factors = factors.Select(Invert);
+          } else {
+            var first = factors.First().ToEnumerable();
+            var remaining = factors.Skip(1).Select(Invert);
+            factors = first.Concat(remaining).ToList();
+          }
+        }
+
         var scalarFactors = factors.Where(IsScalarNode).ToList();
         var remainingFactors = factors.Except(scalarFactors).ToList();