Changeset 5060 for branches/GP.Symbols (TimeLag, Diff, Integral)/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs

Timestamp:

12/07/10 14:11:12 (13 years ago)

Author:

mkommend

Message:

Implemented VariableCondition symbol (ticket #1325).

File:

• branches/GP.Symbols (TimeLag, Diff, Integral)/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs (modified) (4 diffs)

branches/GP.Symbols (TimeLag, Diff, Integral)/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs

@@ -71 +71 @@
       public const byte Integral = 23;
       public const byte Derivative = 24;
+
+      public const byte VariableCondition = 25;
     }
 
@@ -97 +99 @@
       { typeof(TimeLag), OpCodes.TimeLag},
       { typeof(Integral), OpCodes.Integral},
-      { typeof(Derivative), OpCodes.Derivative}
+      { typeof(Derivative), OpCodes.Derivative},
+      { typeof(VariableCondition),OpCodes.VariableCondition}
     };
     private const int ARGUMENT_STACK_SIZE = 1024;
@@ -147 +150 @@
         var variableTreeNode = instr.dynamicNode as LaggedVariableTreeNode;
         instr.iArg0 = (ushort)dataset.GetVariableIndex(variableTreeNode.VariableName);
+      } else if (instr.opCode == OpCodes.VariableCondition) {
+        var variableConditionTreeNode = instr.dynamicNode as VariableConditionTreeNode;
+        instr.iArg0 = (ushort)dataset.GetVariableIndex(variableConditionTreeNode.VariableName);
       }
       return instr;
@@ -344 +350 @@
             return (f_0 + 2 * f_1 - 2 * f_3 - f_4) / 8; // h = 1
           }
+
+        //mkommend: this symbol uses the logistic function f(x) = 1 / (1 + e^(-alpha * x) ) 
+        //to determine the relative amounts of the true and false branch see http://en.wikipedia.org/wiki/Logistic_function
+        case OpCodes.VariableCondition: {
+            var variableConditionTreeNode = (VariableConditionTreeNode)currentInstr.dynamicNode;
+            double variableValue = dataset[row, currentInstr.iArg0];
+            double x = variableValue - variableConditionTreeNode.Threshold;
+            double p = 1 / (1 + Math.Exp(-variableConditionTreeNode.Slope * x));
+
+            double trueBranch = Evaluate();
+            double falseBranch = Evaluate();
+
+            return trueBranch * p + falseBranch * (1 - p);
+          }
         default: throw new NotSupportedException();
       }