def create_input_iter(dataset_builder, batch_size, image_size, dtype, train,
cache):
ds = input_pipeline.create_split(
dataset_builder, batch_size, image_size=image_size, dtype=dtype,
train=train, cache=cache)
it = map(prepare_tf_data, ds)
it = jax_utils.prefetch_to_device(it, 2)
return it
def main(argv):
assert (
len(argv) == 1
), "Please specify arguments via flags. Use --help for instructions"
assert (getattr(elegy.nets.resnet, FLAGS.model, None)
is not None), f"{FLAGS.model} is not defined in elegy.nets.resnet"
assert not os.path.exists(
FLAGS.output_dir
), "Output directory already exists. Delete manually or specify a new one."
os.makedirs(FLAGS.output_dir)
# dataset
dataset_builder = tfds.builder(FLAGS.dataset)
ds_train = input_pipeline.create_split(
dataset_builder,
batch_size=FLAGS.batch_size,
image_size=FLAGS.image_size,
dtype=FLAGS.dtype,
train=True,
cache=FLAGS.cache,
)
ds_valid = input_pipeline.create_split(
dataset_builder,
batch_size=FLAGS.batch_size,
image_size=FLAGS.image_size,
dtype=FLAGS.dtype,
train=False,
cache=FLAGS.cache,
)
N_BATCHES_TRAIN = (dataset_builder.info.splits["train"].num_examples //
FLAGS.batch_size)
N_BATCHES_VALID = (
dataset_builder.info.splits["validation"].num_examples //
FLAGS.batch_size)
# generator that converts tfds dataset batches to jax arrays
def tfds2jax_generator(tf_ds):
for batch in tf_ds:
yield jnp.asarray(batch["image"],
dtype=FLAGS.dtype), jax.device_put(
jnp.asarray(batch["label"]))
# model and optimizer definition
def build_optimizer(lr,
momentum,
steps_per_epoch,
n_epochs,
nesterov,
warmup_epochs=5):
cosine_schedule = optax.cosine_decay_schedule(1,
decay_steps=n_epochs *
steps_per_epoch,
alpha=1e-10)
warmup_schedule = optax.polynomial_schedule(
init_value=0.0,
end_value=1.0,
power=1,
transition_steps=warmup_epochs * steps_per_epoch,
)
schedule = lambda x: jnp.minimum(cosine_schedule(x), warmup_schedule(x)
)
optimizer = optax.sgd(lr, momentum, nesterov=nesterov)
optimizer = optax.chain(optimizer, optax.scale_by_schedule(schedule))
return optimizer
module = getattr(elegy.nets.resnet, FLAGS.model)(dtype=FLAGS.dtype)
model = elegy.Model(
module,
loss=[
elegy.losses.SparseCategoricalCrossentropy(
from_logits=True, weight=FLAGS.loss_scale),
elegy.regularizers.GlobalL2(FLAGS.L2_reg / 2 * FLAGS.loss_scale),
],
metrics=elegy.metrics.SparseCategoricalAccuracy(),
optimizer=build_optimizer(
FLAGS.base_lr / FLAGS.loss_scale,
FLAGS.momentum,
N_BATCHES_TRAIN,
FLAGS.epochs,
FLAGS.nesterov,
),
)
# training
model.fit(
x=tfds2jax_generator(ds_train),
validation_data=tfds2jax_generator(ds_valid),
epochs=FLAGS.epochs,
verbose=2,
steps_per_epoch=N_BATCHES_TRAIN,
validation_steps=N_BATCHES_VALID,
callbacks=[
elegy.callbacks.ModelCheckpoint(FLAGS.output_dir,
save_best_only=True),
elegy.callbacks.TerminateOnNaN(),
elegy.callbacks.TensorBoard(logdir=FLAGS.output_dir),
],
)
