def get_learning_rate(lr_config, global_step):
"""
Instantiate a learning rate operation given a configuration with learning rate, name, and parameters.
:param lr_config: learning rate configuration
:param global_step: global step `Tensor`
:return: learning rate operation
"""
lr = lr_config.rate
name = lr_config.name
if "exponential_decay" == name:
decay = exponential_decay(lr, global_step, **lr_config.params)
elif "inverse_time_decay" == name:
decay = inverse_time_decay(lr, global_step, **lr_config.params)
elif "vaswani" == name:
decay = _transformer_learning_rate(lr_config, global_step)
elif "bert" == name:
decay = _bert_learning_rate(lr_config, global_step)
elif "clr" == name:
decay = cyclic_learning_rate(global_step,
learning_rate=lr_config.rate,
max_lr=lr_config.params.get(
'max_lr', 0.1),
step_size=lr_config.steps_per_epoch *
lr_config.params.get('step_size', 4))
else:
raise ValueError("Unknown learning rate schedule: {}".format(name))
return decay
def testStaircase(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = resource_variable_ops.ResourceVariable(0)
decayed_lr = learning_rate_decay.inverse_time_decay(
initial_lr, step, k, decay_rate, staircase=True)
self.evaluate(variables.global_variables_initializer())
for i in range(k + 1):
expected = initial_lr / (1 + decay_rate * (i // k))
self.assertAllClose(self.evaluate(decayed_lr), expected, 1e-6)
self.evaluate(step.assign_add(1))
def testDecay(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = resource_variable_ops.ResourceVariable(0)
decayed_lr = learning_rate_decay.inverse_time_decay(
initial_lr, step, k, decay_rate)
self.evaluate(variables.global_variables_initializer())
for i in range(k + 1):
expected = initial_lr / (1 + i / k * decay_rate)
self.assertAllClose(self.evaluate(decayed_lr), expected, 1e-6)
self.evaluate(step.assign_add(1))
def testDecay(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = state_ops.variable_op([], dtypes.int32)
assign_step = state_ops.assign(step, 0)
increment_step = state_ops.assign_add(step, 1)
decayed_lr = learning_rate_decay.inverse_time_decay(
initial_lr, step, k, decay_rate)
with self.test_session():
assign_step.op.run()
for i in range(k + 1):
expected = initial_lr / (1 + i / k * decay_rate)
self.assertAllClose(decayed_lr.eval(), expected, 1e-6)
increment_step.op.run()
def testDecay(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = state_ops.variable_op([], dtypes.int32)
assign_step = state_ops.assign(step, 0)
increment_step = state_ops.assign_add(step, 1)
decayed_lr = learning_rate_decay.inverse_time_decay(initial_lr,
step,
k,
decay_rate)
with self.test_session():
assign_step.op.run()
for i in range(k+1):
expected = initial_lr / (1 + i / k * decay_rate)
self.assertAllClose(decayed_lr.eval(), expected, 1e-6)
increment_step.op.run()
def testStaircase(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = gen_state_ops._variable(shape=[], dtype=dtypes.int32,
name="step", container="", shared_name="")
assign_step = state_ops.assign(step, 0)
increment_step = state_ops.assign_add(step, 1)
decayed_lr = learning_rate_decay.inverse_time_decay(initial_lr,
step,
k,
decay_rate,
staircase=True)
with self.test_session():
assign_step.op.run()
for i in range(k+1):
expected = initial_lr / (1 + decay_rate * (i // k))
self.assertAllClose(decayed_lr.eval(), expected, 1e-6)
increment_step.op.run()
def testStaircase(self):
initial_lr = 0.1
k = 10
decay_rate = 0.96
step = gen_state_ops._variable(shape=[], dtype=dtypes.int32,
name="step", container="", shared_name="")
assign_step = state_ops.assign(step, 0)
increment_step = state_ops.assign_add(step, 1)
decayed_lr = learning_rate_decay.inverse_time_decay(initial_lr,
step,
k,
decay_rate,
staircase=True)
with self.test_session():
assign_step.op.run()
for i in range(k+1):
expected = initial_lr / (1 + decay_rate * (i // k))
self.assertAllClose(decayed_lr.eval(), expected, 1e-6)
increment_step.op.run()
def apply_lr_decay(cfg, global_step):
# Learning rate schedule
if cfg.lr_decay is None:
lr = cfg.lr
elif cfg.lr_decay == 'exp':
lr = exponential_decay(cfg.lr,
global_step,
cfg.decay_steps,
cfg.decay_rate,
staircase=cfg.staircase)
elif cfg.lr_decay == 'piecewise':
lr = piecewise_constant(global_step, cfg.lr_boundaries, cfg.lr_values)
elif cfg.lr_decay == 'polynomial':
lr = polynomial_decay(cfg.lr,
global_step,
cfg.decay_steps,
end_learning_rate=cfg.end_lr,
power=cfg.power,
cycle=cfg.staircase)
elif cfg.lr_decay == 'natural_exp':
lr = natural_exp_decay(cfg.lr,
global_step,
cfg.decay_steps,
cfg.decay_rate,
staircase=cfg.staircase)
elif cfg.lr_decay == 'inverse_time':
lr = inverse_time_decay(cfg.lr,
global_step,
cfg.decay_steps,
cfg.decay_rate,
staircase=cfg.staircase)
elif cfg.lr_decay == 'STN':
epoch = tf.cast(global_step / cfg.decay_steps, tf.int32)
lr = cfg.lr * tf.pow(0.5, tf.cast(epoch / 50, cfg._FLOATX))
else:
raise NotImplementedError()
return lr
