Decaying the learning rate

tf.train.exponential_decay(learning_rate, global_step, decay_steps, decay_rate, staircase=False, name=None)

Applies exponential decay to the learning rate.

When training a model, it is often recommended to lower the learning rate as the training progresses. This function applies an exponential decay function to a provided initial learning rate. It requires a global_step value to compute the decayed learning rate. You can just pass a TensorFlow variable that you increment at each training step.

The function returns the decayed learning rate. It is computed as:

decayed_learning_rate = learning_rate *
                        decay_rate ^ (global_step / decay_steps)

If the argument staircase is True, then global_step / decay_steps is an integer division and the decayed learning rate follows a staircase function.

Example: decay every 100000 steps with a base of 0.96:

...
global_step = tf.Variable(0, trainable=False)
starter_learning_rate = 0.1
learning_rate = tf.train.exponential_decay(starter_learning_rate, global_step,
                                           100000, 0.96, staircase=True)
# Passing global_step to minimize() will increment it at each step.
learning_step = (
    tf.train.GradientDescentOptimizer(learning_rate)
    .minimize(...my loss..., global_step=global_step)
)
Args:
  • learning_rate: A scalar float32 or float64 Tensor or a Python number. The initial learning rate.
  • global_step: A scalar int32 or int64 Tensor or a Python number. Global step to use for the decay computation. Must not be negative.
  • decay_steps: A scalar int32 or int64 Tensor or a Python number. Must be positive. See the decay computation above.
  • decay_rate: A scalar float32 or float64 Tensor or a Python number. The decay rate.
  • staircase: Boolean. It True decay the learning rate at discrete intervals
  • name: String. Optional name of the operation. Defaults to 'ExponentialDecay'
Returns:

A scalar Tensor of the same type as learning_rate. The decayed learning rate.