tf.keras.optimizers.Adadelta

Optimizer that implements the Adadelta algorithm.

Inherits From: Optimizer

tf.keras.optimizers.Adadelta(
    learning_rate=0.001,
    rho=0.95,
    epsilon=1e-07,
    name='Adadelta',
    **kwargs
)

Adadelta optimization is a stochastic gradient descent method that is based on adaptive learning rate per dimension to address two drawbacks:

  • The continual decay of learning rates throughout training.
  • The need for a manually selected global learning rate.

Adadelta is a more robust extension of Adagrad that adapts learning rates based on a moving window of gradient updates, instead of accumulating all past gradients. This way, Adadelta continues learning even when many updates have been done. Compared to Adagrad, in the original version of Adadelta you don't have to set an initial learning rate. In this version, the initial learning rate can be set, as in most other Keras optimizers.

learning_rate Initial value for the learning rate: either a floating point value, or a tf.keras.optimizers.schedules.LearningRateSchedule instance. Defaults to 0.001. Note that Adadelta tends to benefit from higher initial learning rate values compared to other optimizers. To match the exact form in the original paper, use 1.0.
rho A Tensor or a floating point value. The decay rate.
epsilon Small floating point value used to maintain numerical stability.
name Optional name prefix for the operations created when applying gradients. Defaults to "Adadelta".
**kwargs Keyword arguments. Allowed to be one of "clipnorm" or "clipvalue". "clipnorm" (float) clips gradients by norm and represents the maximum norm of each parameter; "clipvalue" (float) clips gradient by value and represents the maximum absolute value of each parameter.

ValueError in case of any invalid argument.