RNN¶
- class continual.RNN(input_size, hidden_size, num_layers=1, nonlinearity='tanh', bias=True, dropout=0.0, device=None, dtype=None, *args, **kwargs)[source]¶
Applies a multi-layer Elman RNN with or non-linearity to an input sequence.
For each element in the input sequence, each layer computes the following function:
where is the hidden state at time t, is the input at time t, and is the hidden state of the previous layer at time t-1 or the initial hidden state at time 0. If
nonlinearity
is'relu'
, then is used instead of .- 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
num_layers (int) – Number of recurrent layers. E.g., setting
num_layers=2
would mean stacking two RNNs together to form a stacked RNN, with the second RNN taking in outputs of the first RNN and computing the final results. Default: 1nonlinearity – The non-linearity to use. Can be either
'tanh'
or'relu'
. Default:'tanh'
bias (bool) – If
False
, then the layer does not use bias weights b_ih and b_hh. Default:True
dropout (float) – If non-zero, introduces a Dropout layer on the outputs of each RNN layer except the last layer, with dropout probability equal to
dropout
. Default: 0
- Inputs: input, h_0
input: tensor of shape containing the features of the input sequence. The input can also be a packed variable length sequence. See
torch.nn.utils.rnn.pack_padded_sequence()
ortorch.nn.utils.rnn.pack_sequence()
for details.h_0: tensor of shape containing the initial hidden state for each element in the batch. Defaults to zeros if not provided.
where:
- Outputs: output, h_n
output: tensor of shape containing the output features (h_t) from the last layer of the RNN, for each t. If a
torch.nn.utils.rnn.PackedSequence
has been given as the input, the output will also be a packed sequence.h_n: tensor of shape containing the final hidden state for each element in the batch.
- Variables:
weight_ih_l[k] – the learnable input-hidden weights of the k-th layer, of shape (hidden_size, input_size) for k = 0. Otherwise, the shape is (hidden_size, num_directions * hidden_size)
weight_hh_l[k] – the learnable hidden-hidden weights of the k-th layer, of shape (hidden_size, hidden_size)
bias_ih_l[k] – the learnable input-hidden bias of the k-th layer, of shape (hidden_size)
bias_hh_l[k] – the learnable hidden-hidden bias of the k-th layer, of shape (hidden_size)
Note
All the weights and biases are initialized from where
Note
For bidirectional RNNs are not supported.
Note
Contrary to the module version found in torch.nn, this module assumes batch first, channel next, and temporal dimension last.
Examples:
rnn = co.RNN(input_size=10, hidden_size=20, num_layers=2) # B, C, T x = torch.randn(1, 10, 16) # torch API h0 = torch.randn(2, 1, 20) output, hn = rnn(x, h0) # continual inference API rnn.set_state(h0) firsts = rnn.forward_steps(x[:,:,:-1]) last = rnn.forward_step(x[:,:,-1]) assert torch.allclose(firsts, output[:, :, :-1]) assert torch.allclose(last, output[:, :, -1])