def __init__(self, grammar, insert_delete_probability=0.5):
self.__dict__.update(locals())
# Must save this because we mix in RegenerationProposals
self.my_regeneration_proposal = RegenerationProposal(grammar)
def __init__(self, grammar, insert_delete_probability=0.5):
self.__dict__.update(locals())
# Must save this because we mix in RegenerationProposals
self.my_regeneration_proposal = RegenerationProposal(grammar)
class InsertDeleteProposal(LOTProposal):
"""
This class is a mixture of standard rejection proposals, and insert/delete proposals
TODO: both insert and delete moves compute similar things, so maybe we can collapse them more elgantly?
NOTE: Without these moves, you will often generate a useful part of a function in, say, an AND, and
you can't remove the AND, meaning you will just make it some subtree equal to "True" --
e.g. this allows AND(T, True) -> T, which is what you want. Otherwise, you have trouble moving out of those
NOTE: This does not go on lambdas -- they're too hard to think about for now.. But even "not" doing them, there are asymmetries--we want to not treat them as "replicating rules", so we can't have sampled them, and also can't delete them
"""
def __init__(self, grammar, insert_delete_probability=0.5):
self.__dict__.update(locals())
# Must save this because we mix in RegenerationProposals
self.my_regeneration_proposal = RegenerationProposal(grammar)
def propose_tree(self, t):
# Default regeneration proposal with some probability
if random() >= self.insert_delete_probability:
return self.my_regeneration_proposal.propose_tree(t)
newt = copy(t)
fb = 0.0 # the forward/backward prob we return
sampled=False # so we can see if we didn't do it
if random() < 0.5: # So we insert
# first sample a node (through sample_node_via_iterate, which handles everything well)
for ni, di, resample_p, resample_Z in self.grammar.sample_node_via_iterate(newt):
if ni.args is None: continue # Can't deal with these TODO: CHECK THIS?
# Since it's an insert, see if there is a (replicating) rule that expands
# from ni.returntype to some ni.returntype
replicating_rules = filter(lambda x: x.name != 'lambda' and (x.to is not None) and any([a==ni.returntype for a in x.to]), self.grammar.rules[ni.returntype])
# If there are none, then we can't insert!
if len(replicating_rules) == 0: continue
# choose a replicating rule; NOTE: this is done uniformly in this step, for simplicity
r, gp = weighted_sample(replicating_rules, probs=lambda x: x.p, return_probability=True, log=False)
gp = log(r.p) - sum([x.p for x in self.grammar.rules[ni.returntype]]) # this is the probability overall in the grammar, not my prob of sampling
# Now take the rule and expand the children:
# choose who gets to be ni
nrhs = len( [ x for x in r.to if x == ni.returntype] ) # how many on the rhs are there?
if nrhs == 0: continue
replace_i = randint(0,nrhs-1) # choose the one to replace
## Now expand args but only for the one we don't sample...
args = []
for x in r.to:
if x == ni.returntype:
if replace_i == 0: args.append( copy(ni) ) # if it's the one we replace into
else: args.append( self.grammar.generate(x, d=di+1) ) #else generate like normalized
replace_i -= 1
else:
args.append( self.grammar.generate(x, d=di+1) ) #else generate like normal
# Now we must count the multiple ways we could go forward or back
after_same_children = [ x for x in args if x==ni] # how many are the same after?
#backward_resample_p = sum([ x.resample_p for x in after_same_children]) # if you go back, you can choose any identical kids
# create the new node
sampled = True
ni.setto( FunctionNode(returntype=r.nt, name=r.name, args=args, generation_probability=gp, bv_name=None, bv_args=None, ruleid=r.rid, resample_p=r.resample_p ) )
if sampled:
new_lp_below = sum(map(lambda z: z.log_probability(), filter(isFunctionNode, args))) - ni.log_probability()
newZ = self.grammar.resample_normalizer(newt)
# To sample forward: choose the node ni, choose the replicating rule, choose which "to" to expand (we could have put it on any of the replicating rules that are identical), and genreate the rest of the tree
f = (log(resample_p) - log(resample_Z)) + -log(len(replicating_rules)) + (log(len(after_same_children))-log(nrhs)) + new_lp_below
# To go backwards, choose the inserted rule, and any of the identical children, out of all replicators
b = (log(ni.resample_p) - log(newZ)) + (log(len(after_same_children)) - log(nrhs))
fb = f-b
else: # A delete move!
for ni, di, resample_p, resample_Z in self.grammar.sample_node_via_iterate(newt):
if ni.name == 'lambda': continue # can't do anything
if ni.args is None: continue # Can't deal with these TODO: CHECK THIS?
# Figure out which of my children have the same type as me
replicating_kid_indices = [ i for i in xrange(len(ni.args)) if isFunctionNode(ni.args[i]) and ni.args[i].returntype==ni.returntype]
nrk = len(replicating_kid_indices) # how many replicating kids
if nrk == 0: continue # if no replicating rules here
## We need to compute a few things for the backwards probability
replicating_rules = filter(lambda x: (x.to is not None) and any([a==ni.returntype for a in x.to]), self.grammar.rules[ni.returntype])
if len(replicating_rules) == 0: continue
i = sample1(replicating_kid_indices) # who to promote; NOTE: not done via any weighting
# Now we must count the multiple ways we could go forward or back
# Here, we could have sampled any of them equivalent to ni.args[i]
before_same_children = [ x for x in ni.args if x==ni.args[i] ] # how many are the same after?
# the lp of everything we'd have to create going backwards
old_lp_below = sum(map(lambda z: z.log_probability(), filter(isFunctionNode, ni.args) )) - ni.args[i].log_probability()
# and replace it
sampled = True
ni.setto( copy(ni.args[i]) ) # TODO: copy not necessary here, I think?
if sampled:
newZ = self.grammar.resample_normalizer(newt)
# To go forward, choose the node, and then from all equivalent children
f = (log(resample_p) - log(resample_Z)) + (log(len(before_same_children)) - log(nrk))
# To go back, choose the node, choose the replicating rule, choose where to put it, and generate the rest of the tree
b = (log(ni.resample_p) - log(newZ)) + -log(len(replicating_rules)) + (log(len(before_same_children)) - log(nrk)) + old_lp_below
fb = f-b
# and fix the bound variables, whose depths may have changed
if sampled: newt.fix_bound_variables()
return [newt, fb]
class InsertDeleteProposal(LOTProposal):
"""
This class is a mixture of standard rejection proposals, and insert/delete proposals
TODO: both insert and delete moves compute similar things, so maybe we can collapse them more elgantly?
NOTE: Without these moves, you will often generate a useful part of a function in, say, an AND, and
you can't remove the AND, meaning you will just make it some subtree equal to "True" --
e.g. this allows AND(T, True) -> T, which is what you want. Otherwise, you have trouble moving out of those
NOTE: This does not go on lambdas -- they're too hard to think about for now.. But even "not" doing them, there are asymmetries--we want to not treat them as "replicating rules", so we can't have sampled them, and also can't delete them
"""
def __init__(self, grammar, insert_delete_probability=0.5):
self.__dict__.update(locals())
# Must save this because we mix in RegenerationProposals
self.my_regeneration_proposal = RegenerationProposal(grammar)
def propose_tree(self, t):
# Default regeneration proposal with some probability
if random() >= self.insert_delete_probability:
return self.my_regeneration_proposal.propose_tree(t)
newt = copy(t)
fb = 0.0 # the forward/backward prob we return
sampled = False # so we can see if we didn't do it
if random() < 0.5: # So we insert
# first sample a node (through sample_node_via_iterate, which handles everything well)
for ni, di, resample_p, resample_Z in self.grammar.sample_node_via_iterate(
newt):
if ni.args is None:
continue # Can't deal with these TODO: CHECK THIS?
# Since it's an insert, see if there is a (replicating) rule that expands
# from ni.returntype to some ni.returntype
replicating_rules = filter(
lambda x: x.name != 'lambda' and (x.to is not None) and
any([a == ni.returntype for a in x.to]),
self.grammar.rules[ni.returntype])
# If there are none, then we can't insert!
if len(replicating_rules) == 0: continue
# choose a replicating rule; NOTE: this is done uniformly in this step, for simplicity
r, gp = weighted_sample(replicating_rules,
probs=lambda x: x.p,
return_probability=True,
log=False)
gp = log(r.p) - sum(
[x.p for x in self.grammar.rules[ni.returntype]]
) # this is the probability overall in the grammar, not my prob of sampling
# Now take the rule and expand the children:
# choose who gets to be ni
nrhs = len([x for x in r.to if x == ni.returntype
]) # how many on the rhs are there?
if nrhs == 0: continue
replace_i = randint(0, nrhs - 1) # choose the one to replace
## Now expand args but only for the one we don't sample...
args = []
for x in r.to:
if x == ni.returntype:
if replace_i == 0:
args.append(
copy(ni)) # if it's the one we replace into
else:
args.append(self.grammar.generate(
x, d=di + 1)) #else generate like normalized
replace_i -= 1
else:
args.append(self.grammar.generate(
x, d=di + 1)) #else generate like normal
# Now we must count the multiple ways we could go forward or back
after_same_children = [x for x in args if x == ni
] # how many are the same after?
#backward_resample_p = sum([ x.resample_p for x in after_same_children]) # if you go back, you can choose any identical kids
# create the new node
sampled = True
ni.setto(
FunctionNode(returntype=r.nt,
name=r.name,
args=args,
generation_probability=gp,
bv_name=None,
bv_args=None,
ruleid=r.rid,
resample_p=r.resample_p))
if sampled:
new_lp_below = sum(
map(lambda z: z.log_probability(),
filter(isFunctionNode, args))) - ni.log_probability()
newZ = self.grammar.resample_normalizer(newt)
# To sample forward: choose the node ni, choose the replicating rule, choose which "to" to expand (we could have put it on any of the replicating rules that are identical), and genreate the rest of the tree
f = (log(resample_p) -
log(resample_Z)) + -log(len(replicating_rules)) + (log(
len(after_same_children)) - log(nrhs)) + new_lp_below
# To go backwards, choose the inserted rule, and any of the identical children, out of all replicators
b = (log(ni.resample_p) -
log(newZ)) + (log(len(after_same_children)) - log(nrhs))
fb = f - b
else: # A delete move!
for ni, di, resample_p, resample_Z in self.grammar.sample_node_via_iterate(
newt):
if ni.name == 'lambda': continue # can't do anything
if ni.args is None:
continue # Can't deal with these TODO: CHECK THIS?
# Figure out which of my children have the same type as me
replicating_kid_indices = [
i for i in xrange(len(ni.args))
if isFunctionNode(ni.args[i])
and ni.args[i].returntype == ni.returntype
]
nrk = len(replicating_kid_indices) # how many replicating kids
if nrk == 0: continue # if no replicating rules here
## We need to compute a few things for the backwards probability
replicating_rules = filter(
lambda x: (x.to is not None) and any(
[a == ni.returntype for a in x.to]),
self.grammar.rules[ni.returntype])
if len(replicating_rules) == 0: continue
i = sample1(
replicating_kid_indices
) # who to promote; NOTE: not done via any weighting
# Now we must count the multiple ways we could go forward or back
# Here, we could have sampled any of them equivalent to ni.args[i]
before_same_children = [x for x in ni.args if x == ni.args[i]
] # how many are the same after?
# the lp of everything we'd have to create going backwards
old_lp_below = sum(
map(lambda z: z.log_probability(),
filter(isFunctionNode,
ni.args))) - ni.args[i].log_probability()
# and replace it
sampled = True
ni.setto(copy(
ni.args[i])) # TODO: copy not necessary here, I think?
if sampled:
newZ = self.grammar.resample_normalizer(newt)
# To go forward, choose the node, and then from all equivalent children
f = (log(resample_p) - log(resample_Z)) + (
log(len(before_same_children)) - log(nrk))
# To go back, choose the node, choose the replicating rule, choose where to put it, and generate the rest of the tree
b = (log(ni.resample_p) -
log(newZ)) + -log(len(replicating_rules)) + (log(
len(before_same_children)) - log(nrk)) + old_lp_below
fb = f - b
# and fix the bound variables, whose depths may have changed
if sampled: newt.fix_bound_variables()
return [newt, fb]