mindspore.nn.Adadelta

class mindspore.nn.Adadelta(params, learning_rate=1.0, rho=0.9, epsilon=1e-6, loss_scale=1.0, weight_decay=0.0)

Implements the Adadelta algorithm.

Adadelta is an online Learning and Stochastic Optimization. Refer to paper ADADELTA: AN ADAPTIVE LEARNING RATE METHOD.

\[\begin{split}\begin{array}{ll} \\ accum_{t} = \rho * accum_{t-1} + (1 - \rho) * g_{t}^2 \\ update_{t} = \sqrt{accum\_update_{t-1} + \epsilon} * \frac{g_{t}}{\sqrt{accum_{t} + \epsilon}} \\ accum\_update_{t} = \rho * accum\_update_{t-1} + (1 - \rho) * update_{t}^2 \\ w_{t} = w_{t-1} - \gamma * update_{t} \end{array}\end{split}\]

where \(g\) represents grads, \(\gamma\) represents learning_rate, \(\rho\) represents rho, \(\epsilon\) represents epsilon, \(w\) represents params, \(accum\) represents accumulation, \(accum\_update\) represents accumulation update, \(t\) represents current step.

Note

If parameters are not grouped, the weight_decay in optimizer will be applied on the network parameters without 'beta' or 'gamma' in their names. Users can group parameters to change the strategy of decaying weight. When parameters are grouped, each group can set weight_decay. If not, the weight_decay in optimizer will be applied.

Parameters

• params (Union[list[Parameter], list[dict]]) –

  Must be list of Parameter or list of dict. When the params is a list of dict, the string "params", "lr", "weight_decay", "grad_centralization" and "order_params" are the keys can be parsed.

  • params: Required. Parameters in current group. The value must be a list of Parameter.

  • lr: Optional. If "lr" in the keys, the value of corresponding learning rate will be used. If not, the learning_rate in optimizer will be used. Fixed and dynamic learning rate are supported.

  • weight_decay: Optional. If "weight_decay" in the keys, the value of corresponding weight decay will be used. If not, the weight_decay in the optimizer will be used. It should be noted that weight decay can be a constant value or a Cell. It is a Cell only when dynamic weight decay is applied. Dynamic weight decay is similar to dynamic learning rate, users need to customize a weight decay schedule only with global step as input, and during training, the optimizer calls the instance of WeightDecaySchedule to get the weight decay value of current step.

  • grad_centralization: Optional. Must be Boolean. If "grad_centralization" is in the keys, the set value will be used. If not, the grad_centralization is False by default. This configuration only works on the convolution layer.

  • order_params: Optional. When parameters is grouped, this usually is used to maintain the order of parameters that appeared in the network to improve performance. The value should be parameters whose order will be followed in optimizer. If order_params in the keys, other keys will be ignored and the element of 'order_params' must be in one group of params.

• learning_rate (Union[float, int, Tensor, Iterable, LearningRateSchedule]) –

  Default: 1.0 .

  • float: The fixed learning rate value. Must be equal to or greater than 0.

  • int: The fixed learning rate value. Must be equal to or greater than 0. It will be converted to float.

  • Tensor: Its value should be a scalar or a 1-D vector. For scalar, fixed learning rate will be applied. For vector, learning rate is dynamic, then the i-th step will take the i-th value as the learning rate.

  • Iterable: Learning rate is dynamic. The i-th step will take the i-th value as the learning rate.

  • LearningRateSchedule: Learning rate is dynamic. During training, the optimizer calls the instance of LearningRateSchedule with step as the input to get the learning rate of current step.

• rho (float) – Decay rate, must be in range [0.0, 1.0]. Default: 0.9 .

• epsilon (float) – A small value added for numerical stability, must be non-negative. Default: 1e-6 .

• loss_scale (float) – Value for the loss scale. It must be greater than 0.0. In general, use the default value. Only when FixedLossScaleManager is used for training and the drop_overflow_update in FixedLossScaleManager is set to False , then this value needs to be the same as the loss_scale in FixedLossScaleManager. Refer to class mindspore.amp.FixedLossScaleManager for more details. Default: 1.0 .

• weight_decay (Union[float, int, Cell]) –

  Weight decay (L2 penalty). Default: 0.0 .

  • float: The fixed weight decay value. Must be equal to or greater than 0.

  • int: The fixed weight decay value. Must be equal to or greater than 0. It will be converted to float.

  • Cell: Weight decay is dynamic. During training, the optimizer calls the instance of the Cell with step as the input to get the weight decay value of current step.

Inputs:

• grads (tuple[Tensor]) - The gradients of params in the optimizer, has the same shape and data type as the params in optimizer. With float16 or float32 data type.

Outputs:

Tensor[bool], the value is True .

Raises

• TypeError – If learning_rate is not one of int, float, Tensor, Iterable, LearningRateSchedule.

• TypeError – If element of params is neither Parameter nor dict.

• TypeError – If rho, epsilon or loss_scale is not a float.

• TypeError – If weight_decay is not float, int or cell.

• ValueError – if rho is not in range [0.0, 1.0].

• ValueError – If loss_scale is less than or equal to 0.

• ValueError – If learning_rate, epsilon or weight_decay is less than 0.

Supported Platforms:

Ascend GPU CPU

Examples

>>> import mindspore as ms
>>> import mindspore.nn as nn
>>>
>>> class Net(nn.Cell):
...    def __init__(self):
...        super(Net, self).__init__()
...        self.conv = nn.Conv1d(120, 240, 4)
...        self.fc = nn.Dense(4, 1)
...    def construct(self, x):
...         x = self.conv(x)
...         x = self.fc(x)
...         return x
>>> net = Net()
>>> #1) All parameters use the same learning rate and weight decay
>>> optim = nn.Adadelta(params=net.trainable_params())
>>>
>>> #2) Use parameter groups and set different values
>>> conv_params = list(filter(lambda x: 'conv' in x.name, net.trainable_params()))
>>> no_conv_params = list(filter(lambda x: 'conv' not in x.name, net.trainable_params()))
>>> group_params = [{'params': conv_params, 'weight_decay': 0.01, 'grad_centralization':True},
...                 {'params': no_conv_params, 'lr': 0.01},
...                 {'order_params': net.trainable_params()}]
>>> optim = nn.Adadelta(group_params, learning_rate=0.1, weight_decay=0.0)
>>> # The conv_params's parameters will use default learning rate of 0.1 and weight decay of 0.01 and grad
>>> # centralization of True.
>>> # The no_conv_params's parameters will use learning rate of 0.01 and default weight decay of 0.0 and grad
>>> # centralization of False.
>>> # The final parameters order in which the optimizer will be followed is the value of 'order_params'.
>>>
>>> loss = nn.SoftmaxCrossEntropyWithLogits()
>>> model = ms.train.Model(net, loss_fn=loss, optimizer=optim)