def select(self,pop,cnt = 1):
if cnt == 1:
return prng.choice(pop)
res = []
for i in range(cnt):
res.append(prng.choice(pop))
return res
def _gen(self, cur_sym = 'ST', active_node = None, depth = 0):
#short circuit really large trees
if(active_node and depth > self.max_depth):
self.dsc = self.dsc + 1
active_node.root().delete_circulars()
raise DepthError
depth = depth + 1
#reset derivation symbol
if(str(cur_sym) == 'ST' or self.derive_type == ''):
if(type(cur_sym) == types.StringType):
self.derive_type = cur_sym
else: self.derive_type = cur_sym.node_type
new_active_node = active_node
if type(cur_sym) == types.StringType:
if self.lang.has_key(cur_sym):
rule = prng.choice(self.lang[cur_sym])
for sym in rule:
new_active_node = self._gen(sym,new_active_node,depth)
else:
active_node.root().delete_circulars()
raise SymbolError, "non-terminal symbol not found:%s" % cur_sym
else:
parent = new_active_node
new_active_node = cur_sym.create(parent)
new_active_node.derive_type = self.derive_type
self.derive_type = ''
if parent:
parent.add_child(new_active_node)
while new_active_node.filled() and new_active_node.get_parent():
new_active_node =new_active_node.get_parent()
return new_active_node
def select(self,pop,cnt = 1): #ignore the past in pop
res = []
for i in range(cnt):
res.append(prng.choice(self.choices))
# for chosen in res: self.choices.remove(chosen)
if cnt == 1:
return res[0]
return res
def dict_choice(dict):
tot = 0
for key in dict.keys(): tot = tot + len(dict[key])
index = prng.choice(xrange(0,tot))
for key in dict.keys():
if index >= len(dict[key]):
index = index - len(dict[key])
else:
return key,dict[key][index]
#shouldn't get here
return None,None
def crosser(self,parents):
"""Takes a tuple of two parent tree_genomes. Clone the parents.
From one parent clone, select a random node making sure
that the nodes derive_type is not in the list of symbols
to reject (cross_rejects). From the other parent clone,
choose another random node THAT HAS THE SAME SYMBOL TYPE
and swap the two nodes. If the same symbol is not found,
a new symbol is chosen from clone1 and the process is tried
again up to 10 times. A SymbolError is raised if the symbol
is never found. Otherwise the two crossed clones are returned.
"""
sib1 = parents[0].clone(); sib2 = parents[1].clone()
sis = sib1.root; bro = sib2.root
tries = 50 #try 50 times to find a compatible cross symbol
tried_sym = []
for i in range(tries):
sym,node_a = dict_choice(sis.symbol_table)
if not self.bad_cross_point(sym) and bro.symbol_table.has_key(sym):
break
elif i == (tries - 1):
msg = "chosen symbol not found in dad (%s tries)" % `tries`
raise SymbolError, msg
else: tried_sym.append(sym)
node_b = prng.choice(bro.symbol_table[sym])
idx = 0
try:
for child in node_a.get_parent().children():
if node_a is child: break
else: idx = idx + 1
node_a.get_parent().children()[idx] = node_b
idx = 0
for child in node_b.get_parent().children():
if node_b is child: break
else: idx = idx + 1
except AttributeError:
print 'symbol:',sym
raise NoneError
node_b.get_parent().children()[idx] = node_a
#now get nodes pointing at the correct parents
temp = node_a.get_parent()
node_a.set_parent(node_b.get_parent())
node_b.set_parent(temp)
sib1.evaluated = 0; sib2.evaluated = 0
if self.cross_point.has_key(sym):
self.cross_point[sym] = self.cross_point[sym] + 1
else: self.cross_point[sym] = 1
return sib1,sib2
def evaluate(self,gene):
old = gene.index()
move = prng.choice((-1,1))
return gene.allele_set[old + move]
def evaluate(self,gene):
""" return a randomly chosen value from the genes allele set """
return prng.choice(gene.allele_set)