def testConfigWithLearningRateDecay(self):
with test_utils.use_gpu():
var0 = tf.Variable([[1.0], [2.0]], dtype=tf.float32)
for decay_schedule in [
learning_rate_schedule.InverseTimeDecay(
0.5, decay_steps=1.0, decay_rate=0.1),
learning_rate_schedule.PiecewiseConstantDecay(
[5], [1., .5])
]:
step = 10
opt = gradient_descent.SGD(decay_schedule)
config = opt.get_config()
opt2 = gradient_descent.SGD.from_config(config)
# assert both are equal float values.
self.assertAllEqual(
decay_schedule(step),
opt._get_hyper('learning_rate')(step))
self.assertAllEqual(
decay_schedule(step),
opt2._get_hyper('learning_rate')(step))
loss = lambda: 3 * var0
# learning rate variable is created when calling minimize.
opt.minimize(loss, [var0])
self.evaluate(tf.compat.v1.global_variables_initializer())
config = opt.get_config()
opt3 = gradient_descent.SGD.from_config(config)
self.assertAllEqual(
self.evaluate(opt._get_hyper('learning_rate')(step)),
opt3._get_hyper('learning_rate')(step))
def testPiecewiseConstantEdgeCases(self, serialize):
# Test casting boundaries from int32 to int64.
x_int64 = tf.Variable(0, dtype=tf.int64)
boundaries, values = [1, 2, 3], [0.4, 0.5, 0.6, 0.7]
decayed_lr = learning_rate_schedule.PiecewiseConstantDecay(
boundaries, values)
decayed_lr = _maybe_serialized(decayed_lr, serialize)
self.evaluate(tf.compat.v1.global_variables_initializer())
self.assertAllClose(self.evaluate(decayed_lr(x_int64)), 0.4, 1e-6)
self.evaluate(x_int64.assign(1))
self.assertAllClose(self.evaluate(decayed_lr(x_int64)), 0.4, 1e-6)
self.evaluate(x_int64.assign(2))
self.assertAllClose(self.evaluate(decayed_lr(x_int64)), 0.5, 1e-6)
self.evaluate(x_int64.assign(3))
self.assertAllClose(self.evaluate(decayed_lr(x_int64)), 0.6, 1e-6)
self.evaluate(x_int64.assign(4))
self.assertAllClose(self.evaluate(decayed_lr(x_int64)), 0.7, 1e-6)
def testPiecewiseConstant(self, serialize):
x = tf.Variable(-999)
decayed_lr = learning_rate_schedule.PiecewiseConstantDecay(
[100, 110, 120], [1.0, 0.1, 0.01, 0.001])
decayed_lr = _maybe_serialized(decayed_lr, serialize)
self.evaluate(tf.compat.v1.global_variables_initializer())
self.assertAllClose(self.evaluate(decayed_lr(x)), 1.0, 1e-6)
self.evaluate(x.assign(100))
self.assertAllClose(self.evaluate(decayed_lr(x)), 1.0, 1e-6)
self.evaluate(x.assign(105))
self.assertAllClose(self.evaluate(decayed_lr(x)), 0.1, 1e-6)
self.evaluate(x.assign(110))
self.assertAllClose(self.evaluate(decayed_lr(x)), 0.1, 1e-6)
self.evaluate(x.assign(120))
self.assertAllClose(self.evaluate(decayed_lr(x)), 0.01, 1e-6)
self.evaluate(x.assign(999))
self.assertAllClose(self.evaluate(decayed_lr(x)), 0.001, 1e-6)
def testPiecewiseFunction(self, serialize):
if not tf.executing_eagerly():
self.skipTest("Run on eager mode only.")
del serialize
v = tf.Variable(1.)
def loss_fn():
return v * v
learning_rate = learning_rate_schedule.PiecewiseConstantDecay(
[1.], [1., 0.1])
opt = gradient_descent.SGD(learning_rate=learning_rate)
@tf.function
def minimize():
with tf.GradientTape() as tape:
loss = loss_fn()
g = tape.gradient(loss, [v])
opt.apply_gradients(list(zip(g, [v])))
minimize()
self.assertAllEqual(v.read_value(), -1.0)
def piecewise_constant(x, boundaries, values, name=None):
"""Piecewise constant from boundaries and interval values.
Example: use a learning rate that's 1.0 for the first 100001 steps, 0.5
for the next 10000 steps, and 0.1 for any additional steps.
```python
global_step = tf.Variable(0, trainable=False)
boundaries = [100000, 110000]
values = [1.0, 0.5, 0.1]
learning_rate = tf.compat.v1.train.piecewise_constant(global_step, boundaries,
values)
# Later, whenever we perform an optimization step, we increment global_step.
```
Args:
x: A 0-D scalar `Tensor`. Must be one of the following types: `float32`,
`float64`, `uint8`, `int8`, `int16`, `int32`, `int64`.
boundaries: A list of `Tensor`s or `int`s or `float`s with strictly
increasing entries, and with all elements having the same type as `x`.
values: A list of `Tensor`s or `float`s or `int`s that specifies the values
for the intervals defined by `boundaries`. It should have one more element
than `boundaries`, and all elements should have the same type.
name: A string. Optional name of the operation. Defaults to
'PiecewiseConstant'.
Returns:
A 0-D Tensor. Its value is `values[0]` when `x <= boundaries[0]`,
`values[1]` when `x > boundaries[0]` and `x <= boundaries[1]`, ...,
and values[-1] when `x > boundaries[-1]`.
Raises:
ValueError: if types of `x` and `boundaries` do not match, or types of all
`values` do not match or
the number of elements in the lists does not match.
@compatibility(eager)
When eager execution is enabled, this function returns a function which in
turn returns the decayed learning rate Tensor. This can be useful for changing
the learning rate value across different invocations of optimizer functions.
@end_compatibility
"""
boundaries = tf.nest.map_structure(tf.convert_to_tensor,
tf.nest.flatten(boundaries))
values = tf.nest.map_structure(tf.convert_to_tensor,
tf.nest.flatten(values))
x_recomp = tf.convert_to_tensor(x)
# Avoid explicit conversion to x's dtype. This could result in faulty
# comparisons, for example if floats are converted to integers.
for i, b in enumerate(boundaries):
if b.dtype.base_dtype != x_recomp.dtype.base_dtype:
# We can promote int32 boundaries to int64 without loss of precision.
# This covers the most common case where the user passes in boundaries
# as an array of Python integers.
if (b.dtype.base_dtype == tf.int32
and x_recomp.dtype.base_dtype == tf.int64):
b = tf.cast(b, x_recomp.dtype.base_dtype)
boundaries[i] = b
else:
raise ValueError(
f"`boundaries` ({b.dtype.base_dtype}) must have the same dtype as "
f"x ({x_recomp.dtype.base_dtype}).")
for v in values[1:]:
if v.dtype.base_dtype != values[0].dtype.base_dtype:
raise ValueError(
f"`values` must have elements all with the same dtype "
f"({values[0].dtype.base_dtype} vs {v.dtype.base_dtype}).")
decayed_lr = learning_rate_schedule.PiecewiseConstantDecay(boundaries,
values,
name=name)
if not tf.executing_eagerly():
decayed_lr = decayed_lr(x)
else:
decayed_lr = functools.partial(decayed_lr, x)
return decayed_lr