Changeset 10424 for branches/HeuristicLab.Problems.GPDL/CodeGenerator/RandomSearchCodeGen.cs

Timestamp:

01/29/14 16:17:20 (10 years ago)

Author:

gkronber

Message:

#2026 maximal depth limit for random search

File:

• branches/HeuristicLab.Problems.GPDL/CodeGenerator/RandomSearchCodeGen.cs (modified) (13 diffs)

branches/HeuristicLab.Problems.GPDL/CodeGenerator/RandomSearchCodeGen.cs

@@ -14 +14 @@
     private static double baseTerminalProbability = 0.05; // 5% of all samples are only a terminal node
     private static double terminalProbabilityInc = 0.05; // for each level the probability to sample a terminal grows by 5%
+    private static int maxDepth = 20;
 
     private readonly ?IDENT?Problem problem;
     private readonly Random random;
 
-    private Tree SampleTree(out int steps, out int depth) {
+    private Tree SampleTree(int maxDepth, out int steps, out int depth) {
       steps = 0;
       depth = 0;
       int curDepth = 0;
-      return SampleTree(0, ref steps, ref curDepth, ref depth);
-    }
-
-    private Tree SampleTree(int state, ref int steps, ref int curDepth, ref int depth) {
+      return SampleTree(0, maxDepth, ref steps, ref curDepth, ref depth);
+    }
+
+    private Tree SampleTree(int state, int maxDepth, ref int steps, ref int curDepth, ref int depth) {
       curDepth += 1;
+      Debug.Assert(maxDepth > 0);
       steps += 1;
       depth = Math.Max(depth, curDepth);
@@ -38 +40 @@
         if(Grammar.subtreeCount[state] == 1) {
           var targetStates = Grammar.transition[state];
-          var altIdx = SampleAlternative(random, state, curDepth);
-          var alternative = SampleTree(targetStates[altIdx], ref steps, ref curDepth, ref depth);
+          var altIdx = SampleAlternative(random, maxDepth - 1, state, curDepth);
+          var alternative = SampleTree(targetStates[altIdx], maxDepth - 1, ref steps, ref curDepth, ref depth);
           t = new Tree(altIdx, new Tree[] { alternative });
         } else {
@@ -45 +47 @@
           Tree[] subtrees = new Tree[Grammar.subtreeCount[state]];
           for(int i = 0; i < Grammar.subtreeCount[state]; i++) {
-            subtrees[i] = SampleTree(Grammar.transition[state][i], ref steps, ref curDepth, ref depth);
+            subtrees[i] = SampleTree(Grammar.transition[state][i], maxDepth - 1, ref steps, ref curDepth, ref depth);
           }
           t = new Tree(-1, subtrees); // alternative index is ignored
@@ -57 +59 @@
       switch(state) {
         ?CREATETERMINALNODECODE?
-        default: { throw new ArgumentException(""Unknown state index"" + state); }
-      }
-    }
-
-    private int SampleAlternative(Random random, int state, int depth) {
+        default: { throw new ArgumentException(""Unknown state index "" + state); }
+      }
+    }
+
+    private int SampleAlternative(Random random, int maxDepth, int state, int depth) {
       switch(state) {
 
@@ -71 +73 @@
 
     private double TerminalProbForDepth(int depth) {
+      if(depth>=maxDepth) return 1.0;
       return baseTerminalProbability + depth * terminalProbabilityInc;
     }
@@ -84 +87 @@
       var baseTerminalProbabilityRegex = new Regex(@""--terminalProbBase=(?<prob>.+)"");
       var terminalProbabilityIncRegex = new Regex(@""--terminalProbInc=(?<prob>.+)"");
+      var maxDepthRegex = new Regex(@""--maxDepth=(?<d>.+)"");
+
       var helpRegex = new Regex(@""--help|/\?"");
       
@@ -89 +94 @@
         var baseTerminalProbabilityMatch = baseTerminalProbabilityRegex.Match(arg);
         var terminalProbabilityIncMatch = terminalProbabilityIncRegex.Match(arg);
+        var maxDepthMatch = maxDepthRegex.Match(arg);
         var helpMatch = helpRegex.Match(arg);
         if(helpMatch.Success) { PrintUsage(); Environment.Exit(0); }
@@ -97 +103 @@
            terminalProbabilityInc = double.Parse(terminalProbabilityIncMatch.Groups[""prob""].Captures[0].Value, System.Globalization.CultureInfo.InvariantCulture);
            if(terminalProbabilityInc < 0.0 || terminalProbabilityInc > 1.0) throw new ArgumentException(""terminal probability increment must lie in range [0.0 ... 1.0]"");
+        } else if(maxDepthMatch.Success) {
+           maxDepth = int.Parse(maxDepthMatch.Groups[""d""].Captures[0].Value, System.Globalization.CultureInfo.InvariantCulture);
+           if(maxDepth < 1 || maxDepth > 100) throw new ArgumentException(""max depth must lie in range [1 ... 100]"");
         } else {
            Console.WriteLine(""Unknown switch {0}"", arg); PrintUsage(); Environment.Exit(0); 
@@ -106 +115 @@
       Console.WriteLine();
       Console.WriteLine(""Parameters:"");
+      Console.WriteLine(""\t--maxDepth=<depth>\tSets the maximal depth of sampled trees [Default: 20]"");
       Console.WriteLine(""\t--terminalProbBase=<prob>\tSets the probability of sampling a terminal alternative in a rule [Default: 0.05]"");
       Console.WriteLine(""\t--terminalProbInc=<prob>\tSets the increment for the probability of sampling a terminal alternative for each level in the syntax tree [Default: 0.05]"");
@@ -127 +137 @@
 
         int steps, depth;
-        var _t = SampleTree(out steps, out depth);
+        var _t = SampleTree(maxDepth, out steps, out depth);
+        Debug.Assert(depth <= maxDepth);
+        // _t.PrintTree(0); Console.WriteLine();
         var f = problem.Evaluate(_t);
  
@@ -185 +197 @@
           var hasNonTerminalAlts = nonTerminalAltIndexes.Any();
           if (hasTerminalAlts && hasNonTerminalAlts) {
-            sb.Append("if(random.NextDouble() < TerminalProbForDepth(depth)) {").BeginBlock();
-            GenerateReturnStatement(terminalAltIndexes, sb);
+            sb.Append("if(maxDepth <= 1 || random.NextDouble() < TerminalProbForDepth(depth)) {").BeginBlock();
+            GenerateSampleTerminalAlternativesStatement(terminalAltIndexes, sb);
             sb.Append("} else {");
-            GenerateReturnStatement(nonTerminalAltIndexes, sb);
+            GenerateSampleNonterminalAlternativesStatement(nonTerminalAltIndexes, sb);
             sb.Append("}").EndBlock();
           } else {
@@ -226 +238 @@
       return sb.ToString();
     }
-    private void GenerateReturnStatement(IEnumerable<int> idxs, SourceBuilder sb) {
+    private void GenerateSampleTerminalAlternativesStatement(IEnumerable<int> idxs, SourceBuilder sb) {
       if (idxs.Count() == 1) {
         sb.AppendFormat("return {0};", idxs.Single()).AppendLine();
@@ -234 +246 @@
       }
     }
+    private void GenerateSampleNonterminalAlternativesStatement(IEnumerable<int> idxs, SourceBuilder sb) {
+      if (idxs.Count() == 1) {
+        sb.AppendFormat("return {0};", idxs.Single()).AppendLine();
+      } else {
+        var idxStr = idxs.Aggregate(string.Empty, (str, idx) => str + idx + ", ");
+        sb.AppendLine("{");
+        sb.AppendFormat("var allIdx = new int[] {{ {0} }}; ", idxStr).AppendLine();
+        sb.AppendFormat(
+          "var allowedIdx = (from idx in allIdx let targetState = Grammar.transition[state][idx] where Grammar.minDepth[targetState] <= maxDepth select idx).ToArray();")
+          .AppendLine();
+        sb.AppendLine(
+          "if(allowedIdx.Length==0) { allowedIdx = Enumerable.Range(0, Grammar.transition[state].Length).Except(allIdx).ToArray(); } ")
+          .AppendLine();
+        sb.AppendLine("return allowedIdx[random.Next(allowedIdx.Length)];");
+        sb.AppendLine("}");
+      }
+    }
 
     private void GenerateReturnStatement(int nAlts, SourceBuilder sb) {
-      if (nAlts > 1) {
-        sb.AppendFormat("return random.Next({0});", nAlts).AppendLine();
+      if (nAlts > 1)
+      {
+        sb.AppendLine("{");
+        sb.AppendFormat(
+          "var allowedIdx = (from idx in Enumerable.Range(0, {0}) let targetState = Grammar.transition[state][idx] where Grammar.minDepth[targetState] <= maxDepth select idx).ToArray();", nAlts)
+          .AppendLine();
+        sb.AppendLine("return allowedIdx[random.Next(allowedIdx.Length)];");
+        sb.AppendLine("}");
       } else if (nAlts == 1) {
         sb.AppendLine("return 0; ");