class TestBidirectionalStack(unittest.TestCase):
def setUp(self):
prototype = SimpleRecurrent(dim=3, activation=Tanh())
self.layers = [
Bidirectional(weights_init=Orthogonal(), prototype=prototype)
for _ in range(3)
]
self.stack = RecurrentStack(self.layers)
for fork in self.stack.forks:
fork.weights_init = Identity(1)
fork.biases_init = Constant(0)
self.stack.initialize()
self.x_val = 0.1 * numpy.asarray(
list(itertools.permutations(range(4))), dtype=theano.config.floatX)
self.x_val = (numpy.ones(
(24, 4, 3), dtype=theano.config.floatX) * self.x_val[..., None])
self.mask_val = numpy.ones((24, 4), dtype=theano.config.floatX)
self.mask_val[12:24, 3] = 0
def test_steps(self):
x = tensor.tensor3('x')
mask = tensor.matrix('mask')
calc_stack_layers = [
theano.function([x, mask],
self.stack.apply(x, mask=mask)[i])
for i in range(len(self.layers))
]
stack_layers = [
f(self.x_val, self.mask_val) for f in calc_stack_layers
]
h_val = self.x_val
for stack_layer_value, bidir_net in zip(stack_layers, self.layers):
calc = theano.function([x, mask], bidir_net.apply(x, mask=mask))
simple_layer_value = calc(h_val, self.mask_val)
assert_allclose(stack_layer_value, simple_layer_value, rtol=1e-04)
h_val = simple_layer_value[..., :3]
def test_dims(self):
self.assertEqual(self.stack.get_dim("inputs"), 3)
for i in range(len(self.layers)):
state_name = self.stack.suffix("states", i)
self.assertEqual(self.stack.get_dim(state_name), 6)
class TestBidirectionalStack(unittest.TestCase):
def setUp(self):
prototype = SimpleRecurrent(dim=3, activation=Tanh())
self.layers = [
Bidirectional(weights_init=Orthogonal(), prototype=prototype)
for _ in range(3)]
self.stack = RecurrentStack(self.layers)
for fork in self.stack.forks:
fork.weights_init = Identity(1)
fork.biases_init = Constant(0)
self.stack.initialize()
self.x_val = 0.1 * numpy.asarray(
list(itertools.permutations(range(4))),
dtype=theano.config.floatX)
self.x_val = (numpy.ones((24, 4, 3), dtype=theano.config.floatX) *
self.x_val[..., None])
self.mask_val = numpy.ones((24, 4), dtype=theano.config.floatX)
self.mask_val[12:24, 3] = 0
def test_steps(self):
x = tensor.tensor3('x')
mask = tensor.matrix('mask')
calc_stack_layers = [
theano.function([x, mask], self.stack.apply(x, mask=mask)[i])
for i in range(len(self.layers))]
stack_layers = [
f(self.x_val, self.mask_val) for f in calc_stack_layers]
h_val = self.x_val
for stack_layer_value, bidir_net in zip(stack_layers, self.layers):
calc = theano.function([x, mask], bidir_net.apply(x, mask=mask))
simple_layer_value = calc(h_val, self.mask_val)
assert_allclose(stack_layer_value, simple_layer_value, rtol=1e-04)
h_val = simple_layer_value[..., :3]
def test_dims(self):
self.assertEqual(self.stack.get_dim("inputs"), 3)
for i in range(len(self.layers)):
state_name = self.stack.suffix("states", i)
self.assertEqual(self.stack.get_dim(state_name), 6)
class TestRecurrentStack(unittest.TestCase):
def setUp(self):
depth = 4
self.depth = depth
dim = 3 # don't change, hardwired in the code
transitions = [LSTM(dim=dim) for _ in range(depth)]
self.stack0 = RecurrentStack(transitions,
weights_init=Constant(2),
biases_init=Constant(0))
self.stack0.initialize()
self.stack2 = RecurrentStack(transitions,
weights_init=Constant(2),
biases_init=Constant(0),
skip_connections=True)
self.stack2.initialize()
def do_one_step(self, stack, skip_connections=False, low_memory=False):
depth = self.depth
# batch=2
h0_val = 0.1 * numpy.array([[[1, 1, 0], [0, 1, 1]]] * depth,
dtype=theano.config.floatX)
c0_val = 0.1 * numpy.array([[[1, 1, 0], [0, 1, 1]]] * depth,
dtype=theano.config.floatX)
x_val = 0.1 * numpy.array([range(12), range(12, 24)],
dtype=theano.config.floatX)
# we will use same weights on all layers
W_state2x_val = 2 * numpy.ones((3, 12), dtype=theano.config.floatX)
W_state_val = 2 * numpy.ones((3, 12), dtype=theano.config.floatX)
W_cell_to_in = 2 * numpy.ones((3,), dtype=theano.config.floatX)
W_cell_to_out = 2 * numpy.ones((3,), dtype=theano.config.floatX)
W_cell_to_forget = 2 * numpy.ones((3,), dtype=theano.config.floatX)
kwargs = OrderedDict()
for d in range(depth):
if d > 0:
suffix = RECURRENTSTACK_SEPARATOR + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
kwargs['inputs' + suffix] = tensor.matrix('inputs' + suffix)
kwargs['inputs' + suffix].tag.test_value = x_val
kwargs['states' + suffix] = tensor.matrix('states' + suffix)
kwargs['states' + suffix].tag.test_value = h0_val[d]
kwargs['cells' + suffix] = tensor.matrix('cells' + suffix)
kwargs['cells' + suffix].tag.test_value = c0_val[d]
results = stack.apply(iterate=False, low_memory=low_memory, **kwargs)
next_h = theano.function(inputs=list(kwargs.values()),
outputs=results)
def sigmoid(x):
return 1. / (1. + numpy.exp(-x))
h1_val = []
x_v = x_val
args_val = []
for d in range(depth):
if d == 0 or skip_connections:
args_val.append(x_val)
h0_v = h0_val[d]
args_val.append(h0_v)
c0_v = c0_val[d]
args_val.append(c0_v)
# omitting biases because they are zero
activation = numpy.dot(h0_v, W_state_val) + x_v
if skip_connections and d > 0:
activation += x_val
i_t = sigmoid(activation[:, :3] + c0_v * W_cell_to_in)
f_t = sigmoid(activation[:, 3:6] + c0_v * W_cell_to_forget)
next_cells = f_t * c0_v + i_t * numpy.tanh(activation[:, 6:9])
o_t = sigmoid(activation[:, 9:12] +
next_cells * W_cell_to_out)
h1_v = o_t * numpy.tanh(next_cells)
# current layer output state transformed to input of next
x_v = numpy.dot(h1_v, W_state2x_val)
h1_val.append(h1_v)
res = next_h(*args_val)
for d in range(depth):
assert_allclose(h1_val[d], res[d * 2], rtol=1e-6)
def test_one_step(self):
self.do_one_step(self.stack0)
self.do_one_step(self.stack0, low_memory=True)
self.do_one_step(self.stack2, skip_connections=True)
self.do_one_step(self.stack2, skip_connections=True, low_memory=True)
def do_many_steps(self, stack, skip_connections=False, low_memory=False):
depth = self.depth
# 24 steps
# 4 batch examples
# 12 dimensions per step
x_val = (0.1 * numpy.asarray(
list(itertools.islice(itertools.permutations(range(12)), 0, 24)),
dtype=theano.config.floatX))
x_val = numpy.ones((24, 4, 12),
dtype=theano.config.floatX) * x_val[:, None, :]
# mask the last third of steps
mask_val = numpy.ones((24, 4), dtype=theano.config.floatX)
mask_val[12:24, 3] = 0
# unroll all states and cells for all steps and also initial value
h_val = numpy.zeros((depth, 25, 4, 3), dtype=theano.config.floatX)
c_val = numpy.zeros((depth, 25, 4, 3), dtype=theano.config.floatX)
# we will use same weights on all layers
W_state2x_val = 2 * numpy.ones((3, 12), dtype=theano.config.floatX)
W_state_val = 2 * numpy.ones((3, 12), dtype=theano.config.floatX)
W_cell_to_in = 2 * numpy.ones((3,), dtype=theano.config.floatX)
W_cell_to_out = 2 * numpy.ones((3,), dtype=theano.config.floatX)
W_cell_to_forget = 2 * numpy.ones((3,), dtype=theano.config.floatX)
kwargs = OrderedDict()
for d in range(depth):
if d > 0:
suffix = RECURRENTSTACK_SEPARATOR + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
kwargs['inputs' + suffix] = tensor.tensor3('inputs' + suffix)
kwargs['inputs' + suffix].tag.test_value = x_val
kwargs['mask'] = tensor.matrix('mask')
kwargs['mask'].tag.test_value = mask_val
results = stack.apply(iterate=True, low_memory=low_memory, **kwargs)
calc_h = theano.function(inputs=list(kwargs.values()),
outputs=results)
def sigmoid(x):
return 1. / (1. + numpy.exp(-x))
for i in range(1, 25):
x_v = x_val[i - 1]
h_vs = []
c_vs = []
for d in range(depth):
h_v = h_val[d][i - 1, :, :]
c_v = c_val[d][i - 1, :, :]
activation = numpy.dot(h_v, W_state_val) + x_v
if skip_connections and d > 0:
activation += x_val[i - 1]
i_t = sigmoid(activation[:, :3] + c_v * W_cell_to_in)
f_t = sigmoid(activation[:, 3:6] + c_v * W_cell_to_forget)
c_v1 = f_t * c_v + i_t * numpy.tanh(activation[:, 6:9])
o_t = sigmoid(activation[:, 9:12] +
c_v1 * W_cell_to_out)
h_v1 = o_t * numpy.tanh(c_v1)
h_v = (mask_val[i - 1, :, None] * h_v1 +
(1 - mask_val[i - 1, :, None]) * h_v)
c_v = (mask_val[i - 1, :, None] * c_v1 +
(1 - mask_val[i - 1, :, None]) * c_v)
# current layer output state transformed to input of next
x_v = numpy.dot(h_v, W_state2x_val)
h_vs.append(h_v)
c_vs.append(c_v)
for d in range(depth):
h_val[d][i, :, :] = h_vs[d]
c_val[d][i, :, :] = c_vs[d]
args_val = [x_val]*(depth if skip_connections else 1) + [mask_val]
res = calc_h(*args_val)
for d in range(depth):
assert_allclose(h_val[d][1:], res[d * 2], rtol=1e-4)
assert_allclose(c_val[d][1:], res[d * 2 + 1], rtol=1e-4)
# Also test that initial state is a parameter
for h in results:
initial_states = VariableFilter(roles=[INITIAL_STATE])(
ComputationGraph(h))
assert all(is_shared_variable(initial_state)
for initial_state in initial_states)
def test_many_steps(self):
self.do_many_steps(self.stack0)
self.do_many_steps(self.stack0, low_memory=True)
self.do_many_steps(self.stack2, skip_connections=True)
self.do_many_steps(self.stack2, skip_connections=True, low_memory=True)
def build_model_hard(vocab_size, args, dtype=floatX):
logger.info('Building model ...')
# Parameters for the model
context = args.context
state_dim = args.state_dim
layers = args.layers
skip_connections = args.skip_connections
# Symbolic variables
# In both cases: Time X Batch
x = tensor.lmatrix('features')
y = tensor.lmatrix('targets')
# Build the model
output_names = []
output_dims = []
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
output_names.append("inputs" + suffix)
output_dims.append(state_dim)
lookup = LookupTable(length=vocab_size, dim=state_dim)
lookup.weights_init = initialization.IsotropicGaussian(0.1)
lookup.biases_init = initialization.Constant(0)
fork = Fork(output_names=output_names,
input_dim=args.mini_batch_size,
output_dims=output_dims,
prototype=FeedforwardSequence([lookup.apply]))
transitions = [SimpleRecurrent(dim=state_dim, activation=Tanh())]
for i in range(layers - 1):
mlp = MLP(activations=[Logistic()],
dims=[2 * state_dim, 1],
weights_init=initialization.IsotropicGaussian(0.1),
biases_init=initialization.Constant(0),
name="mlp_" + str(i))
transitions.append(
HardGatedRecurrent(dim=state_dim, mlp=mlp, activation=Tanh()))
rnn = RecurrentStack(transitions, skip_connections=skip_connections)
# dim = layers * state_dim
output_layer = Linear(input_dim=layers * state_dim,
output_dim=vocab_size,
name="output_layer")
# Return list of 3D Tensor, one for each layer
# (Time X Batch X embedding_dim)
pre_rnn = fork.apply(x)
# Give a name to the input of each layer
if skip_connections:
for t in range(len(pre_rnn)):
pre_rnn[t].name = "pre_rnn_" + str(t)
else:
pre_rnn.name = "pre_rnn"
# Prepare inputs for the RNN
kwargs = OrderedDict()
init_states = {}
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if skip_connections:
kwargs['inputs' + suffix] = pre_rnn[d]
elif d == 0:
kwargs['inputs' + suffix] = pre_rnn
init_states[d] = theano.shared(numpy.zeros(
(args.mini_batch_size, state_dim)).astype(floatX),
name='state0_%d' % d)
kwargs['states' + suffix] = init_states[d]
# Apply the RNN to the inputs
h = rnn.apply(low_memory=True, **kwargs)
# Now we have correctly:
# h = [state_1, state_2, state_3 ...]
# Save all the last states
last_states = {}
for d in range(layers):
last_states[d] = h[d][-1, :, :]
# Concatenate all the states
if layers > 1:
h = tensor.concatenate(h, axis=2)
h.name = "hidden_state"
# The updates of the hidden states
updates = []
for d in range(layers):
updates.append((init_states[d], last_states[d]))
presoft = output_layer.apply(h[context:, :, :])
# Define the cost
# Compute the probability distribution
time, batch, feat = presoft.shape
presoft.name = 'presoft'
cross_entropy = Softmax().categorical_cross_entropy(
y[context:, :].flatten(), presoft.reshape((batch * time, feat)))
cross_entropy = cross_entropy / tensor.log(2)
cross_entropy.name = "cross_entropy"
# TODO: add regularisation for the cost
# the log(1) is here in order to differentiate the two variables
# for monitoring
cost = cross_entropy + tensor.log(1)
cost.name = "regularized_cost"
# Initialize the model
logger.info('Initializing...')
fork.initialize()
rnn.weights_init = initialization.Orthogonal()
rnn.biases_init = initialization.Constant(0)
rnn.initialize()
output_layer.weights_init = initialization.IsotropicGaussian(0.1)
output_layer.biases_init = initialization.Constant(0)
output_layer.initialize()
return cost, cross_entropy, updates
def build_model_vanilla(vocab_size, args, dtype=floatX):
logger.info('Building model ...')
# Parameters for the model
context = args.context
state_dim = args.state_dim
layers = args.layers
skip_connections = args.skip_connections
# Symbolic variables
# In both cases: Time X Batch
x = tensor.lmatrix('features')
y = tensor.lmatrix('targets')
# Build the model
output_names = []
output_dims = []
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
output_names.append("inputs" + suffix)
output_dims.append(state_dim)
lookup = LookupTable(length=vocab_size, dim=state_dim)
lookup.weights_init = initialization.IsotropicGaussian(0.1)
lookup.biases_init = initialization.Constant(0)
fork = Fork(output_names=output_names, input_dim=args.mini_batch_size,
output_dims=output_dims,
prototype=FeedforwardSequence(
[lookup.apply]))
transitions = [SimpleRecurrent(dim=state_dim, activation=Tanh())
for _ in range(layers)]
rnn = RecurrentStack(transitions, skip_connections=skip_connections)
# If skip_connections: dim = layers * state_dim
# else: dim = state_dim
output_layer = Linear(
input_dim=skip_connections * layers *
state_dim + (1 - skip_connections) * state_dim,
output_dim=vocab_size, name="output_layer")
# Return list of 3D Tensor, one for each layer
# (Time X Batch X embedding_dim)
pre_rnn = fork.apply(x)
# Give a name to the input of each layer
if skip_connections:
for t in range(len(pre_rnn)):
pre_rnn[t].name = "pre_rnn_" + str(t)
else:
pre_rnn.name = "pre_rnn"
# Prepare inputs for the RNN
kwargs = OrderedDict()
init_states = {}
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if skip_connections:
kwargs['inputs' + suffix] = pre_rnn[d]
elif d == 0:
kwargs['inputs'] = pre_rnn
init_states[d] = theano.shared(
numpy.zeros((args.mini_batch_size, state_dim)).astype(floatX),
name='state0_%d' % d)
kwargs['states' + suffix] = init_states[d]
# Apply the RNN to the inputs
h = rnn.apply(low_memory=True, **kwargs)
# We have
# h = [state, state_1, state_2 ...] if layers > 1
# h = state if layers == 1
# If we have skip connections, concatenate all the states
# Else only consider the state of the highest layer
last_states = {}
if layers > 1:
# Save all the last states
for d in range(layers):
last_states[d] = h[d][-1, :, :]
if skip_connections:
h = tensor.concatenate(h, axis=2)
else:
h = h[-1]
else:
last_states[0] = h[-1, :, :]
h.name = "hidden_state"
# The updates of the hidden states
updates = []
for d in range(layers):
updates.append((init_states[d], last_states[d]))
presoft = output_layer.apply(h[context:, :, :])
# Define the cost
# Compute the probability distribution
time, batch, feat = presoft.shape
presoft.name = 'presoft'
cross_entropy = Softmax().categorical_cross_entropy(
y[context:, :].flatten(),
presoft.reshape((batch * time, feat)))
cross_entropy = cross_entropy / tensor.log(2)
cross_entropy.name = "cross_entropy"
# TODO: add regularisation for the cost
# the log(1) is here in order to differentiate the two variables
# for monitoring
cost = cross_entropy + tensor.log(1)
cost.name = "regularized_cost"
# Initialize the model
logger.info('Initializing...')
fork.initialize()
rnn.weights_init = initialization.Orthogonal()
rnn.biases_init = initialization.Constant(0)
rnn.initialize()
output_layer.weights_init = initialization.IsotropicGaussian(0.1)
output_layer.biases_init = initialization.Constant(0)
output_layer.initialize()
return cost, cross_entropy, updates
def build_fork_lookup(vocab_size, time_length, args):
x = tensor.lmatrix('features')
virtual_dim = 6
state_dim = 6
skip_connections = False
layers = 1
# Build the model
output_names = []
output_dims = []
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
output_names.append("inputs" + suffix)
output_dims.append(virtual_dim)
lookup = LookupTable(length=vocab_size, dim=virtual_dim)
lookup.weights_init = initialization.IsotropicGaussian(0.1)
lookup.biases_init = initialization.Constant(0)
fork = Fork(output_names=output_names, input_dim=time_length,
output_dims=output_dims,
prototype=FeedforwardSequence(
[lookup.apply]))
# Note that this order of the periods makes faster modules flow in slower
# ones with is the opposite of the original paper
transitions = [ClockworkBase(dim=state_dim, activation=Tanh(),
period=2 ** i) for i in range(layers)]
rnn = RecurrentStack(transitions, skip_connections=skip_connections)
# Return list of 3D Tensor, one for each layer
# (Batch X Time X embedding_dim)
pre_rnn = fork.apply(x)
# Give time as the first index for each element in the list:
# (Time X Batch X embedding_dim)
if layers > 1 and skip_connections:
for t in range(len(pre_rnn)):
pre_rnn[t] = pre_rnn[t].dimshuffle(1, 0, 2)
else:
pre_rnn = pre_rnn.dimshuffle(1, 0, 2)
f_pre_rnn = theano.function([x], pre_rnn)
# Prepare inputs for the RNN
kwargs = OrderedDict()
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
if skip_connections:
kwargs['inputs' + suffix] = pre_rnn[d]
else:
kwargs['inputs' + suffix] = pre_rnn
print kwargs
# Apply the RNN to the inputs
h = rnn.apply(low_memory=True, **kwargs)
fork.initialize()
rnn.weights_init = initialization.Orthogonal()
rnn.biases_init = initialization.Constant(0)
rnn.initialize()
f_h = theano.function([x], h)
return f_pre_rnn, f_h
def build_model_soft(vocab_size, args, dtype=floatX):
logger.info('Building model ...')
# Parameters for the model
context = args.context
state_dim = args.state_dim
layers = args.layers
skip_connections = args.skip_connections
# Symbolic variables
# In both cases: Time X Batch
x = tensor.lmatrix('features')
y = tensor.lmatrix('targets')
# Build the model
output_names = []
output_dims = []
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
output_names.append("inputs" + suffix)
output_dims.append(state_dim)
lookup = LookupTable(length=vocab_size, dim=state_dim)
lookup.weights_init = initialization.IsotropicGaussian(0.1)
lookup.biases_init = initialization.Constant(0)
fork = Fork(output_names=output_names, input_dim=args.mini_batch_size,
output_dims=output_dims,
prototype=FeedforwardSequence(
[lookup.apply]))
transitions = [SimpleRecurrent(dim=state_dim, activation=Tanh())]
# Build the MLP
dims = [2 * state_dim]
activations = []
for i in range(args.mlp_layers):
activations.append(Rectifier())
dims.append(state_dim)
# Activation of the last layer of the MLP
if args.mlp_activation == "logistic":
activations.append(Logistic())
elif args.mlp_activation == "rectifier":
activations.append(Rectifier())
elif args.mlp_activation == "hard_logistic":
activations.append(HardLogistic())
else:
assert False
# Output of MLP has dimension 1
dims.append(1)
for i in range(layers - 1):
mlp = MLP(activations=activations, dims=dims,
weights_init=initialization.IsotropicGaussian(0.1),
biases_init=initialization.Constant(0),
name="mlp_" + str(i))
transitions.append(
SoftGatedRecurrent(dim=state_dim,
mlp=mlp,
activation=Tanh()))
rnn = RecurrentStack(transitions, skip_connections=skip_connections)
# dim = layers * state_dim
output_layer = Linear(
input_dim=layers * state_dim,
output_dim=vocab_size, name="output_layer")
# Return list of 3D Tensor, one for each layer
# (Time X Batch X embedding_dim)
pre_rnn = fork.apply(x)
# Give a name to the input of each layer
if skip_connections:
for t in range(len(pre_rnn)):
pre_rnn[t].name = "pre_rnn_" + str(t)
else:
pre_rnn.name = "pre_rnn"
# Prepare inputs for the RNN
kwargs = OrderedDict()
init_states = {}
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if skip_connections:
kwargs['inputs' + suffix] = pre_rnn[d]
elif d == 0:
kwargs['inputs' + suffix] = pre_rnn
init_states[d] = theano.shared(
numpy.zeros((args.mini_batch_size, state_dim)).astype(floatX),
name='state0_%d' % d)
kwargs['states' + suffix] = init_states[d]
# Apply the RNN to the inputs
h = rnn.apply(low_memory=True, **kwargs)
# Now we have:
# h = [state, state_1, gate_value_1, state_2, gate_value_2, state_3, ...]
# Extract gate_values
gate_values = h[2::2]
new_h = [h[0]]
new_h.extend(h[1::2])
h = new_h
# Now we have:
# h = [state, state_1, state_2, ...]
# gate_values = [gate_value_1, gate_value_2, gate_value_3]
for i, gate_value in enumerate(gate_values):
gate_value.name = "gate_value_" + str(i)
# Save all the last states
last_states = {}
for d in range(layers):
last_states[d] = h[d][-1, :, :]
# Concatenate all the states
if layers > 1:
h = tensor.concatenate(h, axis=2)
h.name = "hidden_state"
# The updates of the hidden states
updates = []
for d in range(layers):
updates.append((init_states[d], last_states[d]))
presoft = output_layer.apply(h[context:, :, :])
# Define the cost
# Compute the probability distribution
time, batch, feat = presoft.shape
presoft.name = 'presoft'
cross_entropy = Softmax().categorical_cross_entropy(
y[context:, :].flatten(),
presoft.reshape((batch * time, feat)))
cross_entropy = cross_entropy / tensor.log(2)
cross_entropy.name = "cross_entropy"
# TODO: add regularisation for the cost
# the log(1) is here in order to differentiate the two variables
# for monitoring
cost = cross_entropy + tensor.log(1)
cost.name = "regularized_cost"
# Initialize the model
logger.info('Initializing...')
fork.initialize()
rnn.weights_init = initialization.Orthogonal()
rnn.biases_init = initialization.Constant(0)
rnn.initialize()
output_layer.weights_init = initialization.IsotropicGaussian(0.1)
output_layer.biases_init = initialization.Constant(0)
output_layer.initialize()
return cost, cross_entropy, updates, gate_values
def build_model_lstm(vocab_size, args, dtype=floatX):
logger.info('Building model ...')
# Parameters for the model
context = args.context
state_dim = args.state_dim
layers = args.layers
skip_connections = args.skip_connections
virtual_dim = 4 * state_dim
# Symbolic variables
# In both cases: Time X Batch
x = tensor.lmatrix('features')
y = tensor.lmatrix('targets')
# Build the model
output_names = []
output_dims = []
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if d == 0 or skip_connections:
output_names.append("inputs" + suffix)
output_dims.append(virtual_dim)
lookup = LookupTable(length=vocab_size, dim=virtual_dim)
lookup.weights_init = initialization.IsotropicGaussian(0.1)
lookup.biases_init = initialization.Constant(0)
# Make sure time_length is what we need
fork = Fork(output_names=output_names,
input_dim=args.mini_batch_size,
output_dims=output_dims,
prototype=FeedforwardSequence([lookup.apply]))
transitions = [
LSTM(dim=state_dim, activation=Tanh()) for _ in range(layers)
]
rnn = RecurrentStack(transitions, skip_connections=skip_connections)
# If skip_connections: dim = layers * state_dim
# else: dim = state_dim
output_layer = Linear(input_dim=skip_connections * layers * state_dim +
(1 - skip_connections) * state_dim,
output_dim=vocab_size,
name="output_layer")
# Return list of 3D Tensor, one for each layer
# (Time X Batch X embedding_dim)
pre_rnn = fork.apply(x)
# Give a name to the input of each layer
if skip_connections:
for t in range(len(pre_rnn)):
pre_rnn[t].name = "pre_rnn_" + str(t)
else:
pre_rnn.name = "pre_rnn"
# Prepare inputs for the RNN
kwargs = OrderedDict()
init_states = {}
init_cells = {}
for d in range(layers):
if d > 0:
suffix = '_' + str(d)
else:
suffix = ''
if skip_connections:
kwargs['inputs' + suffix] = pre_rnn[d]
elif d == 0:
kwargs['inputs'] = pre_rnn
init_states[d] = theano.shared(numpy.zeros(
(args.mini_batch_size, state_dim)).astype(floatX),
name='state0_%d' % d)
init_cells[d] = theano.shared(numpy.zeros(
(args.mini_batch_size, state_dim)).astype(floatX),
name='cell0_%d' % d)
kwargs['states' + suffix] = init_states[d]
kwargs['cells' + suffix] = init_cells[d]
# Apply the RNN to the inputs
h = rnn.apply(low_memory=True, **kwargs)
# h = [state, cell, in, forget, out, state_1,
# cell_1, in_1, forget_1, out_1 ...]
last_states = {}
last_cells = {}
for d in range(layers):
last_states[d] = h[5 * d][-1, :, :]
last_cells[d] = h[5 * d + 1][-1, :, :]
# The updates of the hidden states
updates = []
for d in range(layers):
updates.append((init_states[d], last_states[d]))
updates.append((init_cells[d], last_states[d]))
# h = [state, cell, in, forget, out, state_1,
# cell_1, in_1, forget_1, out_1 ...]
# Extract the values
in_gates = h[2::5]
forget_gates = h[3::5]
out_gates = h[4::5]
gate_values = {
"in_gates": in_gates,
"forget_gates": forget_gates,
"out_gates": out_gates
}
h = h[::5]
# Now we have correctly:
# h = [state, state_1, state_2 ...] if layers > 1
# h = [state] if layers == 1
# If we have skip connections, concatenate all the states
# Else only consider the state of the highest layer
if layers > 1:
if skip_connections:
h = tensor.concatenate(h, axis=2)
else:
h = h[-1]
else:
h = h[0]
h.name = "hidden_state"
presoft = output_layer.apply(h[context:, :, :])
# Define the cost
# Compute the probability distribution
time, batch, feat = presoft.shape
presoft.name = 'presoft'
cross_entropy = Softmax().categorical_cross_entropy(
y[context:, :].flatten(), presoft.reshape((batch * time, feat)))
cross_entropy = cross_entropy / tensor.log(2)
cross_entropy.name = "cross_entropy"
# TODO: add regularisation for the cost
# the log(1) is here in order to differentiate the two variables
# for monitoring
cost = cross_entropy + tensor.log(1)
cost.name = "regularized_cost"
# Initialize the model
logger.info('Initializing...')
fork.initialize()
# Dont initialize as Orthogonal if we are about to load new parameters
if args.load_path is not None:
rnn.weights_init = initialization.Constant(0)
else:
rnn.weights_init = initialization.Orthogonal()
rnn.biases_init = initialization.Constant(0)
rnn.initialize()
output_layer.weights_init = initialization.IsotropicGaussian(0.1)
output_layer.biases_init = initialization.Constant(0)
output_layer.initialize()
return cost, cross_entropy, updates, gate_values
