def grow(self, depth=None):
""" Grows a random child node by 1, limited by `depth` (if provided)
and arity restrictions. Returns the new node (or None if no
node can be expanded).
Args:
depth: int (default=None)
Returns:
Node instance (or None)
"""
# Creates a random permutation of child nodes
nodes_depths = list(self.descendants_and_self_with_depths())
shuffle(nodes_depths)
for node, d in nodes_depths:
if len(node.children) >= node.func.arity:
continue
if d >= depth:
continue
if d == depth - 1:
func = Function.random_terminal()
else:
func = Function.random_function()
child = Node(func)
node.add_child(child)
return child
# If no children can be expanded, return None
return None
def grow(self, depth=None):
""" Grows a random child node by 1, limited by `depth` (if provided)
and arity restrictions. Returns the new node (or None if no
node can be expanded).
Args:
depth: int (default=None)
Returns:
Node instance (or None)
"""
# Creates a random permutation of child nodes
nodes_depths = list(self.descendants_and_self_with_depths())
shuffle(nodes_depths)
for node, d in nodes_depths:
if len(node.children) >= node.func.arity:
continue
if d >= depth:
continue
if d == depth - 1:
func = Function.random_terminal()
else:
func = Function.random_function()
child = Node(func)
node.add_child(child)
return child
# If no children can be expanded, return None
return None
def create_grow_tree(depth):
""" Creates a tree using the grow method with depth `depth`. Note
that since grow ends when all leaf nodes are 0-arity, it is
possible that the tree generated by this method has a depth
less than `depth`.
Args:
depth: int
Returns:
Node instance
"""
func = Function.random_function()
root = Node(func)
while True:
if root.grow(depth) is None:
break
return root
def create_grow_tree(depth):
""" Creates a tree using the grow method with depth `depth`. Note
that since grow ends when all leaf nodes are 0-arity, it is
possible that the tree generated by this method has a depth
less than `depth`.
Args:
depth: int
Returns:
Node instance
"""
func = Function.random_function()
root = Node(func)
while True:
if root.grow(depth) is None:
break
return root
def create_full_tree(depth):
""" Creates a tree using the full method with depth `depth`.
Returns the root node.
Args:
depth: int
Returns:
Node instance
"""
if depth == 0:
# Generate a leaf node
terminal = Function.random_terminal()
node = Node(terminal)
return node
else:
# Generate an intermediate node
func = Function.random_function()
node = Node(func)
for _ in range(func.arity):
node.add_child(TreeMethods.create_full_tree(depth - 1))
return node
def create_full_tree(depth):
""" Creates a tree using the full method with depth `depth`.
Returns the root node.
Args:
depth: int
Returns:
Node instance
"""
if depth == 0:
# Generate a leaf node
terminal = Function.random_terminal()
node = Node(terminal)
return node
else:
# Generate an intermediate node
func = Function.random_function()
node = Node(func)
for _ in range(func.arity):
node.add_child(TreeMethods.create_full_tree(depth - 1))
return node