Added a __setitem__ method in PrimitiveTree to check user input. Curr…

…ently, these verifications cover three common errors : - Replacing a primitive by another of a different arity - Appending a subtree to the end without changing the current primitives (this will lead to an "unaccessible" part of the tree, meaning that len(ind) will return a different value than len(ind[ind.searchSubtree(0)]), and that some part of the tree will _not_ be evaluated, which can be seriously misleading) - Inserting an incomplete subtree, for instance [add, 1, 2, 3] (considering that add has an arity of 2), which would mess up the tree A quick testing shows virtually no performance loss over the previous (non-checked) method. Also fix a small bug in the C version of the Ant simulator. --HG-- branch : dev
falconzyx · Jul 16, 2012 · ff0c6ad · ff0c6ad
1 parent d59c2e5
commit ff0c6ad
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Showing 3 changed files with 31 additions and 2 deletions.
diff --git a/deap/gp.py b/deap/gp.py
@@ -51,6 +51,33 @@ def __deepcopy__(self, memo):
         new.__dict__.update(copy.deepcopy(self.__dict__, memo))
         return new
 
+    def __setitem__(self, key, val):
+        # Check for most common errors
+        # Does NOT check for STGP constraints
+        if isinstance(key, slice):
+            if (key.start >= len(self)):
+                raise IndexError, "Invalid slice object (try to assign a %s"\
+                    " in a tree of size %d). Even if this is allowed by the"\
+                    " list object slice setter, this should not be done in"\
+                    " the PrimitiveTree context, as this may lead to an"\
+                    " unpredictable behavior for searchSubtree or evaluate."\
+                     % (key, len(self))
+            total = val[0].arity
+            for node in val[1:]:
+                total += node.arity - 1
+            if total != 0:
+                raise ValueError, "Invalid slice assignation : insertion of"\
+                    " an incomplete subtree is not allowed in PrimitiveTree."\
+                    " A tree is defined as incomplete when some nodes cannot"\
+                    " be mapped to any position in the tree, considering the"\
+                    " primitives' arity. For instance, the tree [sub, 4, 5,"\
+                    " 6] is incomplete if the arity of sub is 2, because it"\
+                    " would produce an orphan node (the 6)."
+        elif val.arity != self[key].arity:
+            raise ValueError, "Invalid node replacement with a node of a"\
+                    " different arity."
+        list.__setitem__(self, key, val)
+
     @property
     def height(self):
         """Return the height of the tree, or the depth of the

diff --git a/examples/gp/ant/AntSimulatorFast.cpp b/examples/gp/ant/AntSimulatorFast.cpp
@@ -367,6 +367,8 @@ PyTypeObject AntSimulatorWrapper_Type = {
 PyObject* progn(PyObject *self, PyObject *args){
     for(Py_ssize_t i = 0; i < PyTuple_Size(args); i++)
         PyObject_CallFunctionObjArgs(PyTuple_GET_ITEM(args, i), NULL);
+    Py_INCREF(Py_None);
+    return Py_None;
 }
 
 static PyMethodDef AntC_functions[] = {

diff --git a/examples/gp/ant/buildAntSimFast.py b/examples/gp/ant/buildAntSimFast.py
@@ -1,9 +1,9 @@
 from distutils.core import setup, Extension
 
-module1 = Extension('cAnt',
+module1 = Extension('AntC',
                     sources = ['AntSimulatorFast.cpp'])
 
-setup (name = 'cAnt',
+setup (name = 'AntC',
        version = '1.0',
        description = 'Fast version of the Ant Simulator (aims to replace the AntSimulator class)',
        ext_modules = [module1])