tfm.optimization.PolynomialDecayWithOffset

A LearningRateSchedule that uses a polynomial decay schedule.

Inherits From: base_lr_class

tfm.optimization.PolynomialDecayWithOffset(
 offset=0, **kwargs
)

It is commonly observed that a monotonically decreasing learning rate, whose degree of change is carefully chosen, results in a better performing model. This schedule applies a polynomial decay function to an optimizer step, given a provided initial_learning_rate, to reach an end_learning_rate in the given decay_steps.

It requires a step value to compute the decayed learning rate. You can just pass a TensorFlow variable that you increment at each training step.

The schedule is a 1-arg callable that produces a decayed learning rate when passed the current optimizer step. This can be useful for changing the learning rate value across different invocations of optimizer functions. It is computed as:

defdecayed_learning_rate(step):
 step = min(step, decay_steps)
 return ((initial_learning_rate - end_learning_rate) *
 (1 - step / decay_steps) ^ (power)
 ) + end_learning_rate

If cycle is True then a multiple of decay_steps is used, the first one that is bigger than step.

defdecayed_learning_rate(step):
 decay_steps = decay_steps * ceil(step / decay_steps)
 return ((initial_learning_rate - end_learning_rate) *
 (1 - step / decay_steps) ^ (power)
 ) + end_learning_rate

You can pass this schedule directly into a tf.keras.optimizers.Optimizer as the learning rate. Example: Fit a model while decaying from 0.1 to 0.01 in 10000 steps using sqrt (i.e. power=0.5):

...
starter_learning_rate = 0.1
end_learning_rate = 0.01
decay_steps = 10000
learning_rate_fn = tf.keras.optimizers.schedules.PolynomialDecay(
 starter_learning_rate,
 decay_steps,
 end_learning_rate,
 power=0.5)
model.compile(optimizer=tf.keras.optimizers.SGD(
 learning_rate=learning_rate_fn),
 loss='sparse_categorical_crossentropy',
 metrics=['accuracy'])
model.fit(data, labels, epochs=5)

The learning rate schedule is also serializable and deserializable using tf.keras.optimizers.schedules.serialize and tf.keras.optimizers.schedules.deserialize.

Child Classes

class base_lr_class

Methods

from_config

@classmethod
from_config(
 config
)

Instantiates a LearningRateSchedule from its config.

get_config

get_config()

__call__

View source

__call__(
 step
)