def forward(self, x, z):
"""Do the WAE forward step
:param x: list of tensors of longs, embed representation of input
:return: float, kl term component of loss
:return: float, recon component of loss
"""
x = lbann.Slice(x, slice_points=str_list([0, self.input_feature_dims]))
x = lbann.Identity(x)
x_emb = lbann.Embedding(x,
num_embeddings=self.dictionary_size,
embedding_dim=self.embedding_size,
name='emb',
weights=self.emb_weights)
# Encoder: x -> z, kl_loss
z_sample = self.forward_encoder(x_emb)
eps = lbann.Gaussian(mean=self.gmean,
stdev=self.gstd,
hint_layer=z_sample)
z_sample = lbann.Add([z_sample, eps])
# Decoder: x, z -> recon_loss
#pred = self.forward_decoder(x_emb, z_sample)
pred, arg_max = self.forward_decoder(x_emb, z_sample)
recon_loss = self.compute_loss(x, pred)
# Hack to remove blocking GPU allreduce in evaluation layer
#kl_loss = lbann.Identity(kl_loss, device='CPU')
recon_loss = lbann.Identity(recon_loss, device='CPU')
z_prior = lbann.Tessellate(
lbann.Reshape(z, dims=str_list([1, self.zdim])),
dims=str_list([self.input_feature_dims, self.zdim]),
)
d_real = self.discriminator0(
lbann.Concatenation([x_emb, z_prior], axis=1))
z_sample0 = lbann.Tessellate(
lbann.Reshape(z_sample, dims=str_list([1, self.zdim])),
dims=str_list([self.input_feature_dims, self.zdim]),
)
y_z_sample = lbann.Concatenation([x_emb, z_sample0], axis=1)
d_fake = self.discriminator0(lbann.StopGradient(y_z_sample))
d_adv = self.discriminator1(y_z_sample) #freeze
return recon_loss, d_real, d_fake, d_adv, arg_max
def forward_decoder(self, x_emb, z):
"""Decoder step, emulating x ~ G(z)
:param x_emb: (n_batch, len(x), d_z) of floats, embeddings for input sentence x
:param z: (n_batch, d_z) of floats, latent vector z
:return: float, recon component of loss
:return: list of ints, reconstructed sentence
"""
# z_0 = z.unsqueeze(1).repeat(1, x_emb.size(1), 1)
# x_input = torch.cat([x_emb, z_0], dim=-1)
z_0 = lbann.Tessellate(
lbann.Reshape(z, dims=str_list([1, 128])),
dims=str_list([self.input_feature_dims, 128]),
)
x_input = lbann.Concatenation(x_emb, z_0, axis=1)
h_0 = self.decoder_lat(z)
# h_0 = h_0.unsqueeze(0).repeat(self.decoder_rnn.num_layers, 1, 1)
h_0 = lbann.Reshape(h_0, dims=str_list([1, 512]))
h_0 = lbann.Tessellate(h_0, dims=str_list((3, 512)))
# output, _ = self.decoder_rnn(x_input, h_0)
output = self.decoder_rnn(x_input, h_0)
# y = self.decoder_fc(output)
y = lbann.ChannelwiseFullyConnected(
output,
output_channel_dims=self.dictionary_size,
bias=True,
name=f'{self.decoder_fc.name}',
weights=self.decoder_fc.weights,
)
# Set datatype of layers
# Note: Depth-first search from y to x_emb and z
stack = [y]
in_stack = {l: True for l in stack}
while stack:
l = stack.pop()
if type(l) not in (lbann.Slice, lbann.Reshape, lbann.Tessellate):
l.datatype = self.datatype
for parent in l.parents:
if parent not in in_stack and parent not in (x_emb, z):
stack.append(parent)
in_stack[parent] = True
return y
def random_projection(indices, num_projections, projection_dim):
# Expand input indices to get an index for each vector entry
# Note: proj_indices(i) = index*projection_dim + i
proj_indices = lbann.WeightedSum(
indices,
scaling_factors=utils.str_list(projection_dim),
)
iota = lbann.WeightsLayer(
dims=utils.str_list(projection_dim),
weights=lbann.Weights(
initializer=lbann.ValueInitializer(
values=utils.str_list(range(projection_dim))),
optimizer=lbann.NoOptimizer(),
),
)
proj_indices = lbann.Sum(
lbann.Tessellate(
lbann.Reshape(proj_indices,
dims=utils.str_list([num_projections, 1])),
dims=utils.str_list([num_projections, projection_dim]),
),
lbann.Tessellate(
lbann.Reshape(iota, dims=utils.str_list([1, projection_dim])),
dims=utils.str_list([num_projections, projection_dim]),
),
)
# Apply hash function and convert to Gaussian distribution
proj = lbann.UniformHash(proj_indices)
ones = lbann.Constant(
value=1,
num_neurons=utils.str_list([num_projections, projection_dim]),
)
eps = 0.001
proj = lbann.ErfInv(
lbann.WeightedSum(
proj,
ones,
scaling_factors=utils.str_list([2 * (1 - eps), -(1 - eps)]),
))
proj = lbann.InstanceNorm(proj)
proj = lbann.WeightedSum(
proj,
scaling_factors=utils.str_list(1 / projection_dim),
)
return proj
def create_position_ids_from_inputs_embeds(self, input_embeds):
sequence_length = self.input_shape[1]
position_ids = range(self.padding_idx + 1,
sequence_length + self.padding_idx + 1)
position_ids = lbann.WeightsLayer(
weights=lbann.Weights(
initializer=lbann.ValueInitializer(
values=str_list(position_ids)),
optimizer=lbann.NoOptimizer(),
),
dims=str_list([sequence_length]),
)
position_ids = lbann.Reshape(position_ids,
dims=str_list([1, sequence_length]))
position_ids = lbann.Tessellate(position_ids,
dims=str_list(self.input_shape[:-1]))
return position_ids
def make_model(
num_epochs,
embed_dim,
num_heads,
label_smoothing,
):
# Embedding weights
var = 2 / (embed_dim + vocab_size) # Glorot initialization
embedding_weights = lbann.Weights(
name='embeddings',
initializer=lbann.NormalInitializer(standard_deviation=math.sqrt(var)),
)
# Input is two sequences of token IDs
input_ = lbann.Input(data_field='samples')
# Get sequences of embedding vectors
# Note: Scale embeddings by sqrt(embed_dim).
# Note: Decoder input is shifted right, so embedding for last
# token isn't needed.
embeddings_tokens = lbann.Identity(
lbann.Slice(
input_,
axis=0,
slice_points=str_list([0, 2 * sequence_length - 1]),
))
embeddings = lbann.Embedding(
embeddings_tokens,
weights=embedding_weights,
num_embeddings=vocab_size,
embedding_dim=embed_dim,
padding_idx=pad_index,
)
embeddings = lbann.WeightedSum(
embeddings,
scaling_factors=str(math.sqrt(embed_dim)),
)
embeddings_slice = lbann.Slice(
embeddings,
axis=0,
slice_points=str_list([0, sequence_length, 2 * sequence_length - 1]),
)
encoder_input = lbann.Identity(embeddings_slice)
decoder_input = lbann.Identity(embeddings_slice)
# Apply transformer model
transformer = lbann.models.Transformer(
hidden_size=embed_dim,
num_heads=num_heads,
name='transformer',
)
result = transformer(
encoder_input,
sequence_length,
decoder_input,
sequence_length - 1,
)
# Reconstruct decoder input
preds = lbann.ChannelwiseFullyConnected(
result,
weights=embedding_weights,
output_channel_dims=[vocab_size],
bias=False,
transpose=True,
)
preds = lbann.ChannelwiseSoftmax(preds)
preds = lbann.Slice(preds,
axis=0,
slice_points=str_list(range(sequence_length)))
preds = [lbann.Identity(preds) for _ in range(sequence_length - 1)]
# Count number of non-pad tokens
label_tokens = lbann.Identity(
lbann.Slice(
input_,
slice_points=str_list([sequence_length + 1, 2 * sequence_length]),
))
pads = lbann.Constant(value=pad_index,
num_neurons=str(sequence_length - 1))
is_not_pad = lbann.NotEqual(label_tokens, pads)
num_not_pad = lbann.Reduction(is_not_pad, mode='sum')
# Cross entropy loss with label smoothing
label_tokens = lbann.Slice(
label_tokens,
slice_points=str_list(range(sequence_length)),
)
label_tokens = [
lbann.Identity(label_tokens) for _ in range(sequence_length - 1)
]
if label_smoothing > 0:
uniform_label = lbann.Constant(value=1 / vocab_size,
num_neurons=str_list([1, vocab_size]))
loss = []
for i in range(sequence_length - 1):
label = lbann.OneHot(label_tokens[i], size=vocab_size)
label = lbann.Reshape(label, dims=str_list([1, vocab_size]))
if label_smoothing > 0:
label = lbann.WeightedSum(
label,
uniform_label,
scaling_factors=str_list(
[1 - label_smoothing, label_smoothing]),
)
loss.append(lbann.CrossEntropy(preds[i], label))
loss = lbann.Concatenation(loss)
# Average cross entropy over non-pad tokens
loss_scales = lbann.Divide(
is_not_pad,
lbann.Tessellate(num_not_pad, hint_layer=is_not_pad),
)
loss = lbann.Multiply(loss, loss_scales)
loss = lbann.Reduction(loss, mode='sum')
# Construct model
metrics = []
callbacks = [lbann.CallbackPrint(), lbann.CallbackTimer()]
return lbann.Model(
num_epochs,
layers=lbann.traverse_layer_graph(input_),
objective_function=loss,
metrics=metrics,
callbacks=callbacks,
)
