PiecewiseDecay¶

class paddle.fluid.dygraph.learning_rate_scheduler. PiecewiseDecay ( boundaries, values, begin, step=1, dtype='float32' ) [source]

Api_attr

imperative

Piecewise decay scheduler.

The algorithm can be described as the code below.

boundaries = [10000, 20000]
values = [1.0, 0.5, 0.1]
if global_step < 10000:
    learning_rate = 1.0
elif 10000 <= global_step < 20000:
    learning_rate = 0.5
else:
    learning_rate = 0.1

Parameters

• boundaries (list) – A list of steps numbers. The type of element in the list is python int.

• values (list) – A list of learning rate values that will be picked during different step boundaries. The type of element in the list is python float.

• begin (int) – The begin step to initialize the global_step in the description above.

• step (int, optional) – The step size used to calculate the new global_step in the description above. The default value is 1.

• dtype (str, optional) – The data type used to create the learning rate variable. The data type can be set as ‘float32’, ‘float64’. The default value is ‘float32’.

Returns

None.

Examples

import paddle.fluid as fluid
boundaries = [10000, 20000]
values = [1.0, 0.5, 0.1]
with fluid.dygraph.guard():
    emb = fluid.dygraph.Embedding( [10, 10] )
    optimizer = fluid.optimizer.SGD(
       learning_rate=fluid.dygraph.PiecewiseDecay(boundaries, values, 0),
       parameter_list = emb.parameters() )