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GRUCell

class torch.nn.GRUCell(input_size, hidden_size, bias=True, device=None, dtype=None)[source]

A gated recurrent unit (GRU) cell.

\[\begin{array}{ll} r = \sigma(W_{ir} x + b_{ir} + W_{hr} h + b_{hr}) \\ z = \sigma(W_{iz} x + b_{iz} + W_{hz} h + b_{hz}) \\ n = \tanh(W_{in} x + b_{in} + r \odot (W_{hn} h + b_{hn})) \\ h' = (1 - z) \odot n + z \odot h \end{array}\]

where \(\sigma\) is the sigmoid function, and \(\odot\) is the Hadamard product.

Parameters:
  • input_size (int) – The number of expected features in the input x

  • hidden_size (int) – The number of features in the hidden state h

  • bias (bool) – If False, then the layer does not use bias weights b_ih and b_hh. Default: True

Inputs: input, hidden
  • input : tensor containing input features

  • hidden : tensor containing the initial hidden state for each element in the batch. Defaults to zero if not provided.

Outputs: h’
  • h’ : tensor containing the next hidden state for each element in the batch

Shape:
  • input: \((N, H_{in})\) or \((H_{in})\) tensor containing input features where \(H_{in}\) = input_size.

  • hidden: \((N, H_{out})\) or \((H_{out})\) tensor containing the initial hidden state where \(H_{out}\) = hidden_size. Defaults to zero if not provided.

  • output: \((N, H_{out})\) or \((H_{out})\) tensor containing the next hidden state.

Variables:
  • weight_ih (torch.Tensor) – the learnable input-hidden weights, of shape (3*hidden_size, input_size)

  • weight_hh (torch.Tensor) – the learnable hidden-hidden weights, of shape (3*hidden_size, hidden_size)

  • bias_ih – the learnable input-hidden bias, of shape (3*hidden_size)

  • bias_hh – the learnable hidden-hidden bias, of shape (3*hidden_size)

Note

All the weights and biases are initialized from \(\mathcal{U}(-\sqrt{k}, \sqrt{k})\) where \(k = \frac{1}{\text{hidden\_size}}\)

On certain ROCm devices, when using float16 inputs this module will use different precision for backward.

Examples:

>>> rnn = nn.GRUCell(10, 20)
>>> input = torch.randn(6, 3, 10)
>>> hx = torch.randn(3, 20)
>>> output = []
>>> for i in range(6):
...     hx = rnn(input[i], hx)
...     output.append(hx)

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