def GTreeGPInitializator(genome, **args):
"""This initializator accepts the follow parameters:
*max_depth*
The max depth of the tree
*method*
The method, accepts "grow", "full" or "ramped"
.. versionadded:: 0.6
The *GTreeGPInitializator* function.
"""
max_depth = genome.get_param("max_depth", 5)
method = genome.get_param("method", "grow")
ga_engine = args["ga_engine"]
if method == "grow":
root = gtree_utils.buildGTreeGPGrow(ga_engine, 0, max_depth)
elif method == "full":
root = gtree_utils.buildGTreeGPFull(ga_engine, 0, max_depth)
elif method == "ramped":
if utils.random_flip_coin(0.5):
root = gtree_utils.buildGTreeGPFull(ga_engine, 0, max_depth)
else:
root = gtree_utils.buildGTreeGPGrow(ga_engine, 0, max_depth)
else:
utils.raise_exception("Unknown tree initialization method [%s] !" % method)
genome.setRoot(root)
genome.processNodes()
assert genome.get_height() <= max_depth
def GTreeGPMutatorSubtree(genome, **args):
""" The mutator of GTreeGP, Subtree Mutator
This mutator will recreate random subtree of the tree using the grow algorithm.
.. versionadded:: 0.6
The *GTreeGPMutatorSubtree* function
"""
if args["pmut"] <= 0.0: return 0
ga_engine = args["ga_engine"]
max_depth = genome.get_param("max_depth", None)
mutations = 0
if max_depth is None:
utils.raise_exception("You must specify the max_depth genome parameter !", ValueError)
if max_depth < 0:
utils.raise_exception("The max_depth must be >= 1, if you want to use GTreeGPMutatorSubtree crossover !", ValueError)
branch_list = genome.nodes_branch
elements = len(branch_list)
for i in xrange(elements):
node = branch_list[i]
assert node is not None
if utils.random_flip_coin(args["pmut"]):
depth = genome.getNodeDepth(node)
mutations += 1
root_subtree = gtree_utils.buildGTreeGPGrow(ga_engine, 0, max_depth-depth)
node_parent = node.getParent()
if node_parent is None:
genome.setRoot(root_subtree)
genome.processNodes()
return mutations
else:
root_subtree.setParent(node_parent)
node_parent.replaceChild(node, root_subtree)
genome.processNodes()
return int(mutations)
