def get_gradients(self, X, Y, weights=1.0):
cost = -(weights * self.log_prob(X, Y)).sum()
params = Selector(self).get_parameters()
gradients = OrderedDict()
if isinstance(weights, float):
for pname, param in params.iteritems():
gradients[param] = tensor.grad(cost, param, consider_constant=[X, Y])
else:
for pname, param in params.iteritems():
gradients[param] = tensor.grad(cost, param, consider_constant=[X, Y, weights])
return gradients
def get_gradients(self, X, Y, weights=1.0):
W_mean, W_ls, b_mean, b_ls = self.parameters
mean, log_sigma = self.sample_expected(Y)
sigma = tensor.exp(log_sigma)
cost = -log_sigma - 0.5 * (X - mean) ** 2 / tensor.exp(2 * log_sigma)
if weights != 1.0:
cost = -weights.dimshuffle(0, "x") * cost
cost_scaled = sigma ** 2 * cost
cost_gscale = (sigma ** 2).sum(axis=1).dimshuffle([0, "x"])
cost_gscale = cost_gscale * cost
gradients = OrderedDict()
params = Selector(self.mlp).get_parameters()
for pname, param in params.iteritems():
gradients[param] = tensor.grad(cost_gscale.sum(), param, consider_constant=[X, Y])
gradients[W_mean] = tensor.grad(cost_scaled.sum(), W_mean, consider_constant=[X, Y])
gradients[b_mean] = tensor.grad(cost_scaled.sum(), b_mean, consider_constant=[X, Y])
gradients[W_ls] = tensor.grad(cost_scaled.sum(), W_ls, consider_constant=[X, Y])
gradients[b_ls] = tensor.grad(cost_scaled.sum(), b_ls, consider_constant=[X, Y])
return gradients
def unify_parameters(self, source_id, dest_id):
source = self.children[source_id]
source_name = self.children[source_id].name
source_prefix = '/' + source_name + '/'
dest_name = self.children[dest_id].name
dest_prefix = '/' + self.name + '/' + dest_name + '/'
source_params = Selector(source).get_parameters()
replaced = []
self.unified_parameters = []
for param, var in source_params.iteritems():
if not param.startswith(source_prefix):
continue
source_param = '/' + self.name + param
param = param[len(source_prefix):]
for unification in self.parameter_unifications_include:
if unification.match(param):
exclude = False
for ex_unification in self.parameter_unifications_exclude:
if ex_unification.match(param):
exclude = True
break
if exclude:
continue
self.replace_parameter(dest_prefix + param, var)
replaced += [dest_prefix + param]
self.unified_parameters += [source_param]
self.unified_parameters = self.convert_names_to_bricks(
set(self.unified_parameters) | set(replaced))
return replaced
def get_gradients(self, X, Y, weights=1.):
cost = -(weights * self.log_prob(X, Y)).sum()
params = Selector(self).get_parameters()
gradients = OrderedDict()
if isinstance(weights, float):
for pname, param in params.iteritems():
gradients[param] = tensor.grad(cost,
param,
consider_constant=[X, Y])
else:
for pname, param in params.iteritems():
gradients[param] = tensor.grad(
cost, param, consider_constant=[X, Y, weights])
return gradients
def get_gradients(self, features, n_samples):
"""Perform inference and calculate gradients.
Returns
-------
log_px : T.fvector
log_psx : T.fvector
gradients : OrderedDict
"""
p_layers = self.p_layers
q_layers = self.q_layers
n_layers = len(p_layers)
batch_size = features.shape[0]
x = replicate_batch(features, n_samples)
# Get Q-samples
samples, log_p, log_q = self.sample_q(x)
# Reshape and sum
samples = unflatten_values(samples, batch_size, n_samples)
log_p = unflatten_values(log_p, batch_size, n_samples)
log_q = unflatten_values(log_q, batch_size, n_samples)
log_p_all = sum(log_p)
log_q_all = sum(log_q)
# Approximate log(p(x))
log_px = logsumexp(log_p_all - log_q_all, axis=-1) - tensor.log(n_samples)
log_psx = (logsumexp((log_p_all - log_q_all) / 2, axis=-1) - tensor.log(n_samples)) * 2.
# Approximate log p(x) and calculate IS weights
w = self.importance_weights(log_p, log_q)
wp = w.reshape((batch_size * n_samples, ))
wq = w.reshape((batch_size * n_samples, ))
wq = wq - (1. / n_samples)
samples = flatten_values(samples, batch_size * n_samples)
gradients = OrderedDict()
for l in xrange(n_layers - 1):
gradients = merge_gradients(gradients, p_layers[l].get_gradients(samples[l], samples[l + 1], weights=wp))
gradients = merge_gradients(gradients, q_layers[l].get_gradients(samples[l + 1], samples[l], weights=wq))
gradients = merge_gradients(gradients, p_layers[-1].get_gradients(samples[-1], weights=wp))
if (self.l1reg > 0.) or (self.l2reg > 0.):
reg_gradients = OrderedDict()
params = Selector(self).get_parameters()
for pname, param in params.iteritems():
if has_roles(param, (WEIGHT,)):
reg_cost = self.l1reg * tensor.sum(abs(param)) + self.l2reg * tensor.sum(param ** 2)
reg_gradients[param] = tensor.grad(reg_cost, param)
gradients = merge_gradients(gradients, reg_gradients)
return log_px, log_psx, gradients
def get_gradients(self, features, n_samples):
log_p_bound = self.log_likelihood_bound(features, n_samples)
gradients = OrderedDict()
params = Selector(self).get_parameters()
for pname, param in params.iteritems():
cost = -log_p_bound.mean() + self.l2reg * tensor.sum(param ** 2)
gradients[param] = tensor.grad(cost, param)
return log_p_bound, gradients
def get_gradients(self, X, Y, weights=1.):
W_mean, W_ls, b_mean, b_ls = self.parameters
mean, log_sigma = self.sample_expected(Y)
sigma = tensor.exp(log_sigma)
cost = -log_sigma - 0.5 * (X - mean)**2 / tensor.exp(2 * log_sigma)
if weights != 1.:
cost = -weights.dimshuffle(0, 'x') * cost
cost_scaled = sigma**2 * cost
cost_gscale = (sigma**2).sum(axis=1).dimshuffle([0, 'x'])
cost_gscale = cost_gscale * cost
gradients = OrderedDict()
params = Selector(self.mlp).get_parameters()
for pname, param in params.iteritems():
gradients[param] = tensor.grad(cost_gscale.sum(),
param,
consider_constant=[X, Y])
gradients[W_mean] = tensor.grad(cost_scaled.sum(),
W_mean,
consider_constant=[X, Y])
gradients[b_mean] = tensor.grad(cost_scaled.sum(),
b_mean,
consider_constant=[X, Y])
gradients[W_ls] = tensor.grad(cost_scaled.sum(),
W_ls,
consider_constant=[X, Y])
gradients[b_ls] = tensor.grad(cost_scaled.sum(),
b_ls,
consider_constant=[X, Y])
return gradients
def get_gradients(self, features, n_samples):
"""Perform inference and calculate gradients.
Returns
-------
log_px : T.fvector
log_psx : T.fvector
gradients : OrderedDict
"""
p_layers = self.p_layers
q_layers = self.q_layers
n_layers = len(p_layers)
batch_size = features.shape[0]
x = replicate_batch(features, n_samples)
# Get Q-samples
samples, log_p, log_q = self.sample_q(x)
# Reshape and sum
samples = unflatten_values(samples, batch_size, n_samples)
log_p = unflatten_values(log_p, batch_size, n_samples)
log_q = unflatten_values(log_q, batch_size, n_samples)
log_p_all = sum(log_p)
log_q_all = sum(log_q)
# Approximate log p(x)
log_px_bound = log_p_all[:,0] - log_q_all[:,0]
log_px = logsumexp(log_p_all-log_q_all, axis=-1) - tensor.log(n_samples)
log_psx = (logsumexp((log_p_all-log_q_all)/2, axis=-1) - tensor.log(n_samples)) * 2.
# Calculate IS weights
w = self.importance_weights(log_p, log_q)
wp = w.reshape( (batch_size*n_samples, ) )
wq = w.reshape( (batch_size*n_samples, ) )
wq = wq - (1./n_samples)
samples = flatten_values(samples, batch_size*n_samples)
gradients = OrderedDict()
for l in xrange(n_layers-1):
gradients = merge_gradients(gradients, p_layers[l].get_gradients(samples[l], samples[l+1], weights=wp))
gradients = merge_gradients(gradients, q_layers[l].get_gradients(samples[l+1], samples[l], weights=wq))
gradients = merge_gradients(gradients, p_layers[-1].get_gradients(samples[-1], weights=wp))
if (self.l1reg > 0.) or (self.l2reg > 0.):
reg_gradients = OrderedDict()
params = Selector(self).get_parameters()
for pname, param in params.iteritems():
if has_roles(param, (WEIGHT,)):
reg_cost = self.l1reg * tensor.sum(abs(param)) + self.l2reg * tensor.sum(param**2)
reg_gradients[param] = tensor.grad(reg_cost, param)
gradients = merge_gradients(gradients, reg_gradients)
self.log_p_bound = log_px_bound
self.log_p = log_px
self.log_ph = log_psx
return log_px, log_psx, gradients
print 'Parsing dataset file...'
vocab = Vocab(dataset_path=args.dataset_path)
source_sentence = tensor.lmatrix('source')
encoder = BidirectionalEncoder(vocab.sequenceLength(), args.embed, args.nhidden)
encoder.weights_init = IsotropicGaussian(args.weight_scale)
encoder.biases_init = Constant(0)
encoder.push_initialization_config()
encoder.bidir.prototype.weights_init = Orthogonal()
encoder.initialize()
print 'Parameter names: '
enc_param_dict = Selector(encoder).get_params()
for name, value in enc_param_dict.iteritems():
print ' {:15}: {}'.format(value.get_value().shape, name)
representation = encoder.apply(source_sentence)
print 'Compiling theano function'
f = theano.function([source_sentence], representation)
reps = np.empty(len(vocab.dataset), dtype=object)
bar = Bar('Encoding', max=len(vocab.dataset))
for idx, sentence in enumerate(vocab.dataset):
reps[idx] = f(sentence).transpose((1, 2, 0))
bar.next()
bar.finish()