# Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import copy import paddle from paddle.fluid import layers, unique_name from paddle.fluid.dygraph import Layer from paddle.fluid.dygraph.layer_object_helper import LayerObjectHelper from paddle.fluid.layers.control_flow import StaticRNN import paddle __all__ = ['BasicGRUUnit', 'basic_gru', 'BasicLSTMUnit', 'basic_lstm'] class BasicGRUUnit(Layer): """ **** BasicGRUUnit class, using basic operators to build GRU The algorithm can be described as the equations below. .. math:: u_t & = actGate(W_ux xu_{t} + W_uh h_{t-1} + b_u) r_t & = actGate(W_rx xr_{t} + W_rh h_{t-1} + b_r) m_t & = actNode(W_cx xm_t + W_ch dot(r_t, h_{t-1}) + b_m) h_t & = dot(u_t, h_{t-1}) + dot((1-u_t), m_t) Args: name_scope(string) : The name scope used to identify parameters and biases hidden_size (integer): The hidden size used in the Unit. param_attr(ParamAttr|None): The parameter attribute for the learnable weight matrix. Note: If it is set to None or one attribute of ParamAttr, gru_unit will create ParamAttr as param_attr. If the Initializer of the param_attr is not set, the parameter is initialized with Xavier. Default: None. bias_attr (ParamAttr|None): The parameter attribute for the bias of GRU unit. If it is set to None or one attribute of ParamAttr, gru_unit will create ParamAttr as bias_attr. If the Initializer of the bias_attr is not set, the bias is initialized zero. Default: None. gate_activation (function|None): The activation function for gates (actGate). Default: 'fluid.layers.sigmoid' activation (function|None): The activation function for cell (actNode). Default: 'fluid.layers.tanh' dtype(string): data type used in this unit Examples: .. code-block:: python import paddle.fluid.layers as layers from paddle.fluid.contrib.layers import BasicGRUUnit input_size = 128 hidden_size = 256 input = layers.data( name = "input", shape = [-1, input_size], dtype='float32') pre_hidden = layers.data( name = "pre_hidden", shape=[-1, hidden_size], dtype='float32') gru_unit = BasicGRUUnit( "gru_unit", hidden_size ) new_hidden = gru_unit( input, pre_hidden ) """ def __init__( self, name_scope, hidden_size, param_attr=None, bias_attr=None, gate_activation=None, activation=None, dtype='float32', ): super().__init__(name_scope, dtype) # reserve old school _full_name and _helper for static graph save load self._full_name = unique_name.generate( name_scope + "/" + self.__class__.__name__ ) self._helper = LayerObjectHelper(self._full_name) self._name = name_scope self._hiden_size = hidden_size self._param_attr = param_attr self._bias_attr = bias_attr self._gate_activation = gate_activation or paddle.nn.functional.sigmoid self._activation = activation or paddle.tanh self._dtype = dtype def _build_once(self, input, pre_hidden): self._input_size = input.shape[-1] assert self._input_size > 0 if self._param_attr is not None and self._param_attr.name is not None: gate_param_attr = copy.deepcopy(self._param_attr) candidate_param_attr = copy.deepcopy(self._param_attr) gate_param_attr.name += "_gate" candidate_param_attr.name += "_candidate" else: gate_param_attr = self._param_attr candidate_param_attr = self._param_attr self._gate_weight = self.create_parameter( attr=gate_param_attr, shape=[self._input_size + self._hiden_size, 2 * self._hiden_size], dtype=self._dtype, ) self._candidate_weight = self.create_parameter( attr=candidate_param_attr, shape=[self._input_size + self._hiden_size, self._hiden_size], dtype=self._dtype, ) if self._bias_attr is not None and self._bias_attr.name is not None: gate_bias_attr = copy.deepcopy(self._bias_attr) candidate_bias_attr = copy.deepcopy(self._bias_attr) gate_bias_attr.name += "_gate" candidate_bias_attr.name += "_candidate" else: gate_bias_attr = self._bias_attr candidate_bias_attr = self._bias_attr self._gate_bias = self.create_parameter( attr=gate_bias_attr, shape=[2 * self._hiden_size], dtype=self._dtype, is_bias=True, ) self._candidate_bias = self.create_parameter( attr=candidate_bias_attr, shape=[self._hiden_size], dtype=self._dtype, is_bias=True, ) def forward(self, input, pre_hidden): concat_input_hidden = layers.concat([input, pre_hidden], 1) gate_input = paddle.matmul(x=concat_input_hidden, y=self._gate_weight) gate_input = paddle.add(gate_input, self._gate_bias) gate_input = self._gate_activation(gate_input) r, u = paddle.split(gate_input, num_or_sections=2, axis=1) r_hidden = r * pre_hidden candidate = paddle.matmul( layers.concat([input, r_hidden], 1), self._candidate_weight ) candidate = paddle.add(candidate, self._candidate_bias) c = self._activation(candidate) new_hidden = u * pre_hidden + (1 - u) * c return new_hidden def basic_gru( input, init_hidden, hidden_size, num_layers=1, sequence_length=None, dropout_prob=0.0, bidirectional=False, batch_first=True, param_attr=None, bias_attr=None, gate_activation=None, activation=None, dtype='float32', name='basic_gru', ): r""" GRU implementation using basic operator, supports multiple layers and bidirectional gru. .. math:: u_t & = actGate(W_ux xu_{t} + W_uh h_{t-1} + b_u) r_t & = actGate(W_rx xr_{t} + W_rh h_{t-1} + b_r) m_t & = actNode(W_cx xm_t + W_ch dot(r_t, h_{t-1}) + b_m) h_t & = dot(u_t, h_{t-1}) + dot((1-u_t), m_t) Args: input (Variable): GRU input tensor, if batch_first = False, shape should be ( seq_len x batch_size x input_size ) if batch_first = True, shape should be ( batch_size x seq_len x hidden_size ) init_hidden(Variable|None): The initial hidden state of the GRU This is a tensor with shape ( num_layers x batch_size x hidden_size) if is_bidirec = True, shape should be ( num_layers*2 x batch_size x hidden_size) and can be reshaped to tensor with ( num_layers x 2 x batch_size x hidden_size) to use. If it's None, it will be set to all 0. hidden_size (int): Hidden size of the GRU num_layers (int): The total number of layers of the GRU sequence_length (Variabe|None): A Tensor (shape [batch_size]) stores each real length of each instance, This tensor will be convert to a mask to mask the padding ids If it's None means NO padding ids dropout_prob(float|0.0): Dropout prob, dropout ONLY works after rnn output of each layers, NOT between time steps bidirectional (bool|False): If it is bidirectional batch_first (bool|True): The shape format of the input and output tensors. If true, the shape format should be :attr:`[batch_size, seq_len, hidden_size]`. If false, the shape format should be :attr:`[seq_len, batch_size, hidden_size]`. By default this function accepts input and emits output in batch-major form to be consistent with most of data format, though a bit less efficient because of extra transposes. param_attr(ParamAttr|None): The parameter attribute for the learnable weight matrix. Note: If it is set to None or one attribute of ParamAttr, gru_unit will create ParamAttr as param_attr. If the Initializer of the param_attr is not set, the parameter is initialized with Xavier. Default: None. bias_attr (ParamAttr|None): The parameter attribute for the bias of GRU unit. If it is set to None or one attribute of ParamAttr, gru_unit will create ParamAttr as bias_attr. If the Initializer of the bias_attr is not set, the bias is initialized zero. Default: None. gate_activation (function|None): The activation function for gates (actGate). Default: 'fluid.layers.sigmoid' activation (function|None): The activation function for cell (actNode). Default: 'fluid.layers.tanh' dtype(string): data type used in this unit name(string): name used to identify parameters and biases Returns: rnn_out(Tensor),last_hidden(Tensor) - rnn_out is result of GRU hidden, with shape (seq_len x batch_size x hidden_size) \ if is_bidirec set to True, shape will be ( seq_len x batch_sze x hidden_size*2) - last_hidden is the hidden state of the last step of GRU \ shape is ( num_layers x batch_size x hidden_size ) \ if is_bidirec set to True, shape will be ( num_layers*2 x batch_size x hidden_size), can be reshaped to a tensor with shape( num_layers x 2 x batch_size x hidden_size) Examples: .. code-block:: python import paddle.fluid.layers as layers from paddle.fluid.contrib.layers import basic_gru batch_size = 20 input_size = 128 hidden_size = 256 num_layers = 2 dropout = 0.5 bidirectional = True batch_first = False input = layers.data( name = "input", shape = [-1, batch_size, input_size], dtype='float32') pre_hidden = layers.data( name = "pre_hidden", shape=[-1, hidden_size], dtype='float32') sequence_length = layers.data( name="sequence_length", shape=[-1], dtype='int32') rnn_out, last_hidden = basic_gru( input, pre_hidden, hidden_size, num_layers = num_layers, \ sequence_length = sequence_length, dropout_prob=dropout, bidirectional = bidirectional, \ batch_first = batch_first) """ fw_unit_list = [] for i in range(num_layers): new_name = name + "_layers_" + str(i) if param_attr is not None and param_attr.name is not None: layer_param_attr = copy.deepcopy(param_attr) layer_param_attr.name += "_fw_w_" + str(i) else: layer_param_attr = param_attr if bias_attr is not None and bias_attr.name is not None: layer_bias_attr = copy.deepcopy(bias_attr) layer_bias_attr.name += "_fw_b_" + str(i) else: layer_bias_attr = bias_attr fw_unit_list.append( BasicGRUUnit( new_name, hidden_size, layer_param_attr, layer_bias_attr, gate_activation, activation, dtype, ) ) if bidirectional: bw_unit_list = [] for i in range(num_layers): new_name = name + "_reverse_layers_" + str(i) if param_attr is not None and param_attr.name is not None: layer_param_attr = copy.deepcopy(param_attr) layer_param_attr.name += "_bw_w_" + str(i) else: layer_param_attr = param_attr if bias_attr is not None and bias_attr.name is not None: layer_bias_attr = copy.deepcopy(bias_attr) layer_bias_attr.name += "_bw_b_" + str(i) else: layer_bias_attr = bias_attr bw_unit_list.append( BasicGRUUnit( new_name, hidden_size, layer_param_attr, layer_bias_attr, gate_activation, activation, dtype, ) ) if batch_first: input = paddle.transpose(input, [1, 0, 2]) mask = None if sequence_length: max_seq_len = paddle.shape(input)[0] mask = layers.sequence_mask( sequence_length, maxlen=max_seq_len, dtype='float32' ) mask = paddle.transpose(mask, [1, 0]) direc_num = 1 if bidirectional: direc_num = 2 if init_hidden: init_hidden = paddle.reshape( init_hidden, shape=[num_layers, direc_num, -1, hidden_size] ) def get_single_direction_output( rnn_input, unit_list, mask=None, direc_index=0 ): rnn = StaticRNN() with rnn.step(): step_input = rnn.step_input(rnn_input) if mask: step_mask = rnn.step_input(mask) for i in range(num_layers): if init_hidden: pre_hidden = rnn.memory(init=init_hidden[i, direc_index]) else: pre_hidden = rnn.memory( batch_ref=rnn_input, shape=[-1, hidden_size], ref_batch_dim_idx=1, ) new_hidden = unit_list[i](step_input, pre_hidden) if mask: new_hidden = paddle.tensor.math._multiply_with_axis( new_hidden, step_mask, axis=0 ) - paddle.tensor.math._multiply_with_axis( pre_hidden, (step_mask - 1), axis=0 ) rnn.update_memory(pre_hidden, new_hidden) rnn.step_output(new_hidden) step_input = new_hidden if dropout_prob is not None and dropout_prob > 0.0: step_input = paddle.nn.functional.dropout( step_input, p=dropout_prob, ) rnn.step_output(step_input) rnn_out = rnn() last_hidden_array = [] rnn_output = rnn_out[-1] for i in range(num_layers): last_hidden = rnn_out[i] last_hidden = last_hidden[-1] last_hidden_array.append(last_hidden) last_hidden_output = layers.concat(last_hidden_array, axis=0) last_hidden_output = paddle.reshape( last_hidden_output, shape=[num_layers, -1, hidden_size] ) return rnn_output, last_hidden_output # seq_len, batch_size, hidden_size fw_rnn_out, fw_last_hidden = get_single_direction_output( input, fw_unit_list, mask, direc_index=0 ) if bidirectional: bw_input = paddle.reverse(input, axis=[0]) bw_mask = None if mask: bw_mask = paddle.reverse(mask, axis=[0]) bw_rnn_out, bw_last_hidden = get_single_direction_output( bw_input, bw_unit_list, bw_mask, direc_index=1 ) bw_rnn_out = paddle.reverse(bw_rnn_out, axis=[0]) rnn_out = layers.concat([fw_rnn_out, bw_rnn_out], axis=2) last_hidden = layers.concat([fw_last_hidden, bw_last_hidden], axis=1) last_hidden = paddle.reshape( last_hidden, shape=[num_layers * direc_num, -1, hidden_size] ) if batch_first: rnn_out = paddle.transpose(rnn_out, [1, 0, 2]) return rnn_out, last_hidden else: rnn_out = fw_rnn_out last_hidden = fw_last_hidden if batch_first: rnn_out = paddle.transpose(rnn_out, [1, 0, 2]) return rnn_out, last_hidden def basic_lstm( input, init_hidden, init_cell, hidden_size, num_layers=1, sequence_length=None, dropout_prob=0.0, bidirectional=False, batch_first=True, param_attr=None, bias_attr=None, gate_activation=None, activation=None, forget_bias=1.0, dtype='float32', name='basic_lstm', ): r""" LSTM implementation using basic operators, supports multiple layers and bidirectional LSTM. .. math:: i_t &= \sigma(W_{ix}x_{t} + W_{ih}h_{t-1} + b_i) f_t &= \sigma(W_{fx}x_{t} + W_{fh}h_{t-1} + b_f + forget_bias ) o_t &= \sigma(W_{ox}x_{t} + W_{oh}h_{t-1} + b_o) \\tilde{c_t} &= tanh(W_{cx}x_t + W_{ch}h_{t-1} + b_c) c_t &= f_t \odot c_{t-1} + i_t \odot \\tilde{c_t} h_t &= o_t \odot tanh(c_t) Args: input (Variable): lstm input tensor, if batch_first = False, shape should be ( seq_len x batch_size x input_size ) if batch_first = True, shape should be ( batch_size x seq_len x hidden_size ) init_hidden(Variable|None): The initial hidden state of the LSTM This is a tensor with shape ( num_layers x batch_size x hidden_size) if is_bidirec = True, shape should be ( num_layers*2 x batch_size x hidden_size) and can be reshaped to a tensor with shape ( num_layers x 2 x batch_size x hidden_size) to use. If it's None, it will be set to all 0. init_cell(Variable|None): The initial hidden state of the LSTM This is a tensor with shape ( num_layers x batch_size x hidden_size) if is_bidirec = True, shape should be ( num_layers*2 x batch_size x hidden_size) and can be reshaped to a tensor with shape ( num_layers x 2 x batch_size x hidden_size) to use. If it's None, it will be set to all 0. hidden_size (int): Hidden size of the LSTM num_layers (int): The total number of layers of the LSTM sequence_length (Variabe|None): A tensor (shape [batch_size]) stores each real length of each instance, This tensor will be convert to a mask to mask the padding ids If it's None means NO padding ids dropout_prob(float|0.0): Dropout prob, dropout ONLY work after rnn output of each layers, NOT between time steps bidirectional (bool|False): If it is bidirectional batch_first (bool|True): The shape format of the input and output tensors. If true, the shape format should be :attr:`[batch_size, seq_len, hidden_size]`. If false, the shape format should be :attr:`[seq_len, batch_size, hidden_size]`. By default this function accepts input and emits output in batch-major form to be consistent with most of data format, though a bit less efficient because of extra transposes. param_attr(ParamAttr|None): The parameter attribute for the learnable weight matrix. Note: If it is set to None or one attribute of ParamAttr, lstm_unit will create ParamAttr as param_attr. If the Initializer of the param_attr is not set, the parameter is initialized with Xavier. Default: None. bias_attr (ParamAttr|None): The parameter attribute for the bias of LSTM unit. If it is set to None or one attribute of ParamAttr, lstm_unit will create ParamAttr as bias_attr. If the Initializer of the bias_attr is not set, the bias is initialized zero. Default: None. gate_activation (function|None): The activation function for gates (actGate). Default: 'fluid.layers.sigmoid' activation (function|None): The activation function for cell (actNode). Default: 'fluid.layers.tanh' forget_bias (float|1.0) : Forget bias used to compute the forget gate dtype(string): Data type used in this unit name(string): Name used to identify parameters and biases Returns: rnn_out(Tensor), last_hidden(Tensor), last_cell(Tensor) - rnn_out is the result of LSTM hidden, shape is (seq_len x batch_size x hidden_size) \ if is_bidirec set to True, it's shape will be ( seq_len x batch_sze x hidden_size*2) - last_hidden is the hidden state of the last step of LSTM \ with shape ( num_layers x batch_size x hidden_size ) \ if is_bidirec set to True, it's shape will be ( num_layers*2 x batch_size x hidden_size), and can be reshaped to a tensor ( num_layers x 2 x batch_size x hidden_size) to use. - last_cell is the hidden state of the last step of LSTM \ with shape ( num_layers x batch_size x hidden_size ) \ if is_bidirec set to True, it's shape will be ( num_layers*2 x batch_size x hidden_size), and can be reshaped to a tensor ( num_layers x 2 x batch_size x hidden_size) to use. Examples: .. code-block:: python import paddle.fluid.layers as layers from paddle.fluid.contrib.layers import basic_lstm batch_size = 20 input_size = 128 hidden_size = 256 num_layers = 2 dropout = 0.5 bidirectional = True batch_first = False input = layers.data( name = "input", shape = [-1, batch_size, input_size], dtype='float32') pre_hidden = layers.data( name = "pre_hidden", shape=[-1, hidden_size], dtype='float32') pre_cell = layers.data( name = "pre_cell", shape=[-1, hidden_size], dtype='float32') sequence_length = layers.data( name="sequence_length", shape=[-1], dtype='int32') rnn_out, last_hidden, last_cell = basic_lstm( input, pre_hidden, pre_cell, \ hidden_size, num_layers = num_layers, \ sequence_length = sequence_length, dropout_prob=dropout, bidirectional = bidirectional, \ batch_first = batch_first) """ fw_unit_list = [] for i in range(num_layers): new_name = name + "_layers_" + str(i) if param_attr is not None and param_attr.name is not None: layer_param_attr = copy.deepcopy(param_attr) layer_param_attr.name += "_fw_w_" + str(i) else: layer_param_attr = param_attr if bias_attr is not None and bias_attr.name is not None: layer_bias_attr = copy.deepcopy(bias_attr) layer_bias_attr.name += "_fw_b_" + str(i) else: layer_bias_attr = bias_attr fw_unit_list.append( BasicLSTMUnit( new_name, hidden_size, param_attr=layer_param_attr, bias_attr=layer_bias_attr, gate_activation=gate_activation, activation=activation, forget_bias=forget_bias, dtype=dtype, ) ) if bidirectional: bw_unit_list = [] for i in range(num_layers): new_name = name + "_reverse_layers_" + str(i) if param_attr is not None and param_attr.name is not None: layer_param_attr = copy.deepcopy(param_attr) layer_param_attr.name += "_bw_w_" + str(i) else: layer_param_attr = param_attr if bias_attr is not None and bias_attr.name is not None: layer_bias_attr = copy.deepcopy(bias_attr) layer_bias_attr.name += "_bw_b_" + str(i) else: layer_bias_attr = param_attr bw_unit_list.append( BasicLSTMUnit( new_name, hidden_size, param_attr=layer_param_attr, bias_attr=layer_bias_attr, gate_activation=gate_activation, activation=activation, forget_bias=forget_bias, dtype=dtype, ) ) if batch_first: input = paddle.transpose(input, [1, 0, 2]) mask = None if sequence_length: max_seq_len = paddle.shape(input)[0] mask = layers.sequence_mask( sequence_length, maxlen=max_seq_len, dtype='float32' ) mask = paddle.transpose(mask, [1, 0]) direc_num = 1 if bidirectional: direc_num = 2 # convert to [num_layers, 2, batch_size, hidden_size] if init_hidden: init_hidden = paddle.reshape( init_hidden, shape=[num_layers, direc_num, -1, hidden_size] ) init_cell = paddle.reshape( init_cell, shape=[num_layers, direc_num, -1, hidden_size] ) # forward direction def get_single_direction_output( rnn_input, unit_list, mask=None, direc_index=0 ): rnn = StaticRNN() with rnn.step(): step_input = rnn.step_input(rnn_input) if mask: step_mask = rnn.step_input(mask) for i in range(num_layers): if init_hidden: pre_hidden = rnn.memory(init=init_hidden[i, direc_index]) pre_cell = rnn.memory(init=init_cell[i, direc_index]) else: pre_hidden = rnn.memory( batch_ref=rnn_input, shape=[-1, hidden_size] ) pre_cell = rnn.memory( batch_ref=rnn_input, shape=[-1, hidden_size] ) new_hidden, new_cell = unit_list[i]( step_input, pre_hidden, pre_cell ) if mask: new_hidden = paddle.tensor.math._multiply_with_axis( new_hidden, step_mask, axis=0 ) - paddle.tensor.math._multiply_with_axis( pre_hidden, (step_mask - 1), axis=0 ) new_cell = paddle.tensor.math._multiply_with_axis( new_cell, step_mask, axis=0 ) - paddle.tensor.math._multiply_with_axis( pre_cell, (step_mask - 1), axis=0 ) rnn.update_memory(pre_hidden, new_hidden) rnn.update_memory(pre_cell, new_cell) rnn.step_output(new_hidden) rnn.step_output(new_cell) step_input = new_hidden if dropout_prob is not None and dropout_prob > 0.0: step_input = paddle.nn.functional.dropout( step_input, p=dropout_prob, mode='upscale_in_train', ) rnn.step_output(step_input) rnn_out = rnn() last_hidden_array = [] last_cell_array = [] rnn_output = rnn_out[-1] for i in range(num_layers): last_hidden = rnn_out[i * 2] last_hidden = last_hidden[-1] last_hidden_array.append(last_hidden) last_cell = rnn_out[i * 2 + 1] last_cell = last_cell[-1] last_cell_array.append(last_cell) last_hidden_output = layers.concat(last_hidden_array, axis=0) last_hidden_output = paddle.reshape( last_hidden_output, shape=[num_layers, -1, hidden_size] ) last_cell_output = layers.concat(last_cell_array, axis=0) last_cell_output = paddle.reshape( last_cell_output, shape=[num_layers, -1, hidden_size] ) return rnn_output, last_hidden_output, last_cell_output # seq_len, batch_size, hidden_size fw_rnn_out, fw_last_hidden, fw_last_cell = get_single_direction_output( input, fw_unit_list, mask, direc_index=0 ) if bidirectional: bw_input = paddle.reverse(input, axis=[0]) bw_mask = None if mask: bw_mask = paddle.reverse(mask, axis=[0]) bw_rnn_out, bw_last_hidden, bw_last_cell = get_single_direction_output( bw_input, bw_unit_list, bw_mask, direc_index=1 ) bw_rnn_out = paddle.reverse(bw_rnn_out, axis=[0]) rnn_out = layers.concat([fw_rnn_out, bw_rnn_out], axis=2) last_hidden = layers.concat([fw_last_hidden, bw_last_hidden], axis=1) last_hidden = paddle.reshape( last_hidden, shape=[num_layers * direc_num, -1, hidden_size] ) last_cell = layers.concat([fw_last_cell, bw_last_cell], axis=1) last_cell = paddle.reshape( last_cell, shape=[num_layers * direc_num, -1, hidden_size] ) if batch_first: rnn_out = paddle.transpose(rnn_out, [1, 0, 2]) return rnn_out, last_hidden, last_cell else: rnn_out = fw_rnn_out last_hidden = fw_last_hidden last_cell = fw_last_cell if batch_first: rnn_out = paddle.transpose(rnn_out, [1, 0, 2]) return rnn_out, last_hidden, last_cell class BasicLSTMUnit(Layer): r""" **** BasicLSTMUnit class, Using basic operator to build LSTM The algorithm can be described as the code below. .. math:: i_t &= \sigma(W_{ix}x_{t} + W_{ih}h_{t-1} + b_i) f_t &= \sigma(W_{fx}x_{t} + W_{fh}h_{t-1} + b_f + forget_bias ) o_t &= \sigma(W_{ox}x_{t} + W_{oh}h_{t-1} + b_o) \\tilde{c_t} &= tanh(W_{cx}x_t + W_{ch}h_{t-1} + b_c) c_t &= f_t \odot c_{t-1} + i_t \odot \\tilde{c_t} h_t &= o_t \odot tanh(c_t) - $W$ terms denote weight matrices (e.g. $W_{ix}$ is the matrix of weights from the input gate to the input) - The b terms denote bias vectors ($bx_i$ and $bh_i$ are the input gate bias vector). - sigmoid is the logistic sigmoid function. - $i, f, o$ and $c$ 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 $h$. - The :math:`\odot` is the element-wise product of the vectors. - :math:`tanh` is the activation functions. - :math:`\\tilde{c_t}` is also called candidate hidden state, which is computed based on the current input and the previous hidden state. Args: name_scope(string) : The name scope used to identify parameter and bias name hidden_size (integer): The hidden size used in the Unit. param_attr(ParamAttr|None): The parameter attribute for the learnable weight matrix. Note: If it is set to None or one attribute of ParamAttr, lstm_unit will create ParamAttr as param_attr. If the Initializer of the param_attr is not set, the parameter is initialized with Xavier. Default: None. bias_attr (ParamAttr|None): The parameter attribute for the bias of LSTM unit. If it is set to None or one attribute of ParamAttr, lstm_unit will create ParamAttr as bias_attr. If the Initializer of the bias_attr is not set, the bias is initialized as zero. Default: None. gate_activation (function|None): The activation function for gates (actGate). Default: 'fluid.layers.sigmoid' activation (function|None): The activation function for cells (actNode). Default: 'fluid.layers.tanh' forget_bias(float|1.0): forget bias used when computing forget gate dtype(string): data type used in this unit Examples: .. code-block:: python import paddle.fluid.layers as layers from paddle.fluid.contrib.layers import BasicLSTMUnit input_size = 128 hidden_size = 256 input = layers.data( name = "input", shape = [-1, input_size], dtype='float32') pre_hidden = layers.data( name = "pre_hidden", shape=[-1, hidden_size], dtype='float32') pre_cell = layers.data( name = "pre_cell", shape=[-1, hidden_size], dtype='float32') lstm_unit = BasicLSTMUnit( "gru_unit", hidden_size) new_hidden, new_cell = lstm_unit( input, pre_hidden, pre_cell ) """ def __init__( self, name_scope, hidden_size, param_attr=None, bias_attr=None, gate_activation=None, activation=None, forget_bias=1.0, dtype='float32', ): super().__init__(name_scope, dtype) # reserve old school _full_name and _helper for static graph save load self._full_name = unique_name.generate( name_scope + "/" + self.__class__.__name__ ) self._helper = LayerObjectHelper(self._full_name) self._name = name_scope self._hiden_size = hidden_size self._param_attr = param_attr self._bias_attr = bias_attr self._gate_activation = gate_activation or paddle.nn.functional.sigmoid self._activation = activation or paddle.tanh self._forget_bias = layers.fill_constant( [1], dtype=dtype, value=forget_bias ) self._forget_bias.stop_gradient = False self._dtype = dtype def _build_once(self, input, pre_hidden, pre_cell): self._input_size = input.shape[-1] assert self._input_size > 0 self._weight = self.create_parameter( attr=self._param_attr, shape=[self._input_size + self._hiden_size, 4 * self._hiden_size], dtype=self._dtype, ) self._bias = self.create_parameter( attr=self._bias_attr, shape=[4 * self._hiden_size], dtype=self._dtype, is_bias=True, ) def forward(self, input, pre_hidden, pre_cell): concat_input_hidden = layers.concat([input, pre_hidden], 1) gate_input = paddle.matmul(x=concat_input_hidden, y=self._weight) gate_input = paddle.add(gate_input, self._bias) i, j, f, o = paddle.split(gate_input, num_or_sections=4, axis=-1) new_cell = paddle.add( paddle.multiply( pre_cell, paddle.nn.functional.sigmoid(paddle.add(f, self._forget_bias)), ), paddle.multiply(paddle.nn.functional.sigmoid(i), paddle.tanh(j)), ) new_hidden = paddle.tanh(new_cell) * paddle.nn.functional.sigmoid(o) return new_hidden, new_cell