diff --git a/paddle/operators/lstm_op.cc b/paddle/operators/lstm_op.cc index 3b90b64b4effacf7240fb1bee8c0aa44251ad727..afb095a04e73c2f09b828c01630ef2347ff49613 100644 --- a/paddle/operators/lstm_op.cc +++ b/paddle/operators/lstm_op.cc @@ -117,7 +117,7 @@ class LSTMOpMaker : public framework::OpProtoAndCheckerMaker { AddInput("C0", "(Tensor, optional) the initial cell state is an optional " "input. This is a tensor with shape (N x D), where N is the " - "batch size. `H0` and `C0` can be NULL but only at the same time") + "batch size. `H0` and `C0` can be NULL but only at the same time.") .AsDispensable(); AddInput("Weight", "(Tensor) the learnable hidden-hidden weights." diff --git a/python/paddle/v2/fluid/layers/nn.py b/python/paddle/v2/fluid/layers/nn.py index 00460850bf5ec553143d76ee5c20578aab98f4db..7d61d111a8ae033f4b976a2dc45064949ac216f9 100644 --- a/python/paddle/v2/fluid/layers/nn.py +++ b/python/paddle/v2/fluid/layers/nn.py @@ -206,6 +206,102 @@ def dynamic_lstm(input, cell_activation='tanh', candidate_activation='tanh', dtype='float32'): + """ + **Dynamic LSTM Layer** + + The defalut implementation is diagonal/peephole connection + (https://arxiv.org/pdf/1402.1128.pdf), the formula is as follows: + + .. math:: + + i_t & = \sigma(W_{ix}x_{t} + W_{ih}h_{t-1} + W_{ic}c_{t-1} + b_i) + + f_t & = \sigma(W_{fx}x_{t} + W_{fh}h_{t-1} + W_{fc}c_{t-1} + b_f) + + \\tilde{c_t} & = act_g(W_{cx}x_t + W_{ch}h_{t-1} + b_c) + + o_t & = \sigma(W_{ox}x_{t} + W_{oh}h_{t-1} + W_{oc}c_t + b_o) + + c_t & = f_t \odot c_{t-1} + i_t \odot \\tilde{c_t} + + h_t & = o_t \odot act_h(c_t) + + where the :math:`W` terms denote weight matrices (e.g. :math:`W_{xi}` is + the matrix of weights from the input gate to the input), :math:`W_{ic}, \ + W_{fc}, W_{oc}` are diagonal weight matrices for peephole connections. In + our implementation, we use vectors to reprenset these diagonal weight + matrices. The :math:`b` terms denote bias vectors (:math:`b_i` is the input + gate bias vector), :math:`\sigma` is the non-line activations, such as + logistic sigmoid function, and :math:`i, f, o` and :math:`c` are the input + gate, forget gate, output gate, and cell activation vectors, respectively, + all of which have the same size as the cell output activation vector :math:`h`. + + The :math:`\odot` is the element-wise product of the vectors. :math:`act_g` + and :math:`act_h` are the cell input and cell output activation functions + and `tanh` is usually used for them. :math:`\\tilde{c_t}` is also called + candidate hidden state, which is computed based on the current input and + the previous hidden state. + + Set `use_peepholes` to `False` to disable peephole connection. The formula + is omitted here, please refer to the paper + http://www.bioinf.jku.at/publications/older/2604.pdf for details. + + Note that these :math:`W_{xi}x_{t}, W_{xf}x_{t}, W_{xc}x_{t}, W_{xo}x_{t}` + operations on the input :math:`x_{t}` are NOT included in this operator. + Users can choose to use fully-connect layer before LSTM layer. + + Args: + input(Variable): The input of dynamic_lstm layer, which supports + variable-time length input sequence. The underlying + tensor in this Variable is a matrix with shape + (T X 4D), where T is the total time steps in this + mini-batch, D is the hidden size. + size(int): 4 * hidden size. + param_attr(ParamAttr): The parameter attribute for the learnable + hidden-hidden weights. + + - The shape is (D x 4D), where D is the hidden + size. + - Weights = {:math:`W_{ch}, W_{ih}, \ + W_{fh}, W_{oh}`} + bias_attr(ParamAttr): The bias attribute for the learnable bias + weights, which contains two parts, input-hidden + bias weights and peephole connections weights if + setting `use_peepholes` to `True`. + + 1. `use_peepholes = False` + - The shape is (1 x 4D). + - Biases = {:math:`b_c, b_i, b_f, b_o`}. + 2. `use_peepholes = True` + - The shape is (1 x 7D). + - Biases = { :math:`b_c, b_i, b_f, b_o, W_{ic}, \ + W_{fc}, W_{oc}`}. + use_peepholes(bool): Whether to enable diagonal/peephole connections, + default `True`. + is_reverse(bool): Whether to compute reversed LSTM, default `False`. + gate_activation(str): The activation for input gate, forget gate and + output gate. Choices = ["sigmoid", "tanh", "relu", + "identity"], default "sigmoid". + cell_activation(str): The activation for cell output. Choices = ["sigmoid", + "tanh", "relu", "identity"], default "tanh". + candidate_activation(str): The activation for candidate hidden state. + Choices = ["sigmoid", "tanh", "relu", "identity"], + default "tanh". + dtype(str): Data type. Choices = ["float32", "float64"], default "float32". + + Returns: + tuple: The hidden state, and cell state of LSTM. The shape of both \ + is (T x D), and lod is the same with the `input`. + + Examples: + .. code-block:: python + + hidden_dim = 512 + forward_proj = fluid.layers.fc(input=input_seq, size=hidden_dim * 4, + act=None, bias_attr=None) + forward, _ = fluid.layers.dynamic_lstm( + input=forward_proj, size=hidden_dim * 4, use_peepholes=False) + """ helper = LayerHelper('lstm', **locals()) size = size / 4 weight = helper.create_parameter(