Changeset 12024 for branches/HeuristicLab.Problems.GrammaticalOptimization/HeuristicLab.Common/ExpressionExtender.cs

Timestamp:

02/17/15 16:03:49 (10 years ago)

Author:

gkronber

Message:

#2283: changed handling of inverse expressions in transformation of expressions to canonical form

File:

• branches/HeuristicLab.Problems.GrammaticalOptimization/HeuristicLab.Common/ExpressionExtender.cs (modified) (9 diffs)

branches/HeuristicLab.Problems.GrammaticalOptimization/HeuristicLab.Common/ExpressionExtender.cs

@@ -11 +11 @@
 namespace HeuristicLab.Algorithms.Bandits {
   // helper to create canonical forms of expressions
-  // NOTE: Not implemented yet (see unit test for divisions)
   // TODO: change symbolicregressionpoly10problem to use this class
   // this does not support expressions with constants (in transformations we assume constant opt is used)
@@ -19 +18 @@
     // supports the grammar
     // G(E):
-    //     E -> V | V+E | V-E | V*E | V%E | V/E | (E) 
+    //     E -> V | V+E | V-E | V*E | V%E | (E) 
     //     V -> <variables>
     //     ";
 
-    // might produce expressions of the form |/x
+    // might produce expressions of the form /x (= 1/x)
     // the pipe symbol | is used for the constant one (in comparison to other constants)
     private string sentence;
@@ -31 +30 @@
       InitLex(phrase);
       var e = CanonicalExpr();
-      return e.ToString(); 
+      return e.ToString();
     }
 
@@ -97 +96 @@
           if (!f.IsSimpleFactor && f.Expr.Terms.Count == 1) {
             foreach (var invF in f.Expr.Terms.First().Factors) {
-              if (invF.ToString() == "|") continue;
+              if (invF.ToString() == "1") continue;
               invF.Invert();
               factors.Add(invF);
@@ -173 +172 @@
       var results = new List<Factor>(factors);
       foreach (var f in factorsArr) {
-        if (f.ToString() == "|") results.Remove(f);
-        if (f.ToString() == "|/(|)") results.Remove(f);
+        if (f.ToString() == "1") results.Remove(f);
+        if (f.ToString() == "1/(1)") results.Remove(f);
         if (f.IsInverse) {
           // find matching
@@ -185 +184 @@
             results.Remove(match);
             if (!results.Any())
-              results.Insert(idx, new Factor('|')); // when the factor is the last one then insert a one
+              results.Insert(idx, new Factor('1')); // when the factor is the last one then insert a one
 
             // also mark as cancelled in the factorsArr
             idx = Array.IndexOf(factorsArr, match);
-            factorsArr[idx] = new Factor('|');
+            factorsArr[idx] = new Factor('1');
           }
         }
       }
-      // remove all unnecessary "1* factors"
-
-      if (results.Count == 0) results.Add(new Factor('|'));
+      if (results.Count == 0) results.Add(new Factor('1'));
       return results;
     }
@@ -230 +227 @@
           var countComp = Factors.Count().CompareTo(other.Factors.Count());
           if (countComp != 0) return countComp;
-          return string.Join("", Factors).CompareTo(string.Join("", other.Factors));
+          foreach (var pair in Factors.Zip(other.Factors, Tuple.Create)) {
+            var fComp = pair.Item1.CompareTo(pair.Item2);
+            if (fComp != 0) return fComp;
+          }
+          return 0;
         }
       }
@@ -304 +305 @@
         var s = Expr == null ? symbol.ToString() : "(" + expr.ToString() + ")";
         if (IsInverse) {
-          return "|/" + s;
+          return "/" + s;
         } else return s;
       }
@@ -356 +357 @@
 
       public override string ToString() {
-        // if (Inverse && Terms.Count > 1)
-        //   return "(" + string.Join("+", Terms) + ")";
-        // else if (Inverse && Terms.Count == 1) {
-        //   return Terms.First().ToString().Replace("%", "#").Replace("*", "%").Replace("#", "*");
-        // } else
         return string.Join("+", Terms);
       }