Merge pull request #7694 from pkuyym/fix-7691

Add python wrapper for sequence reshape operator.

Author: pkuyym

doc/api/v2/fluid/layers.rst

@@ -504,3 +504,8 @@ l2_normalize
 ------------
 ..  autofunction:: paddle.v2.fluid.layers.l2_normalize
     :noindex:
+
+sequence_reshape
+----------------
+..  autofunction:: paddle.v2.fluid.layers.sequence_reshape
+    :noindex:

python/paddle/v2/fluid/layers/nn.py

@@ -28,7 +28,7 @@
     'batch_norm', 'beam_search_decode', 'conv2d_transpose', 'sequence_expand',
     'lstm_unit', 'reduce_sum', 'reduce_mean', 'reduce_max', 'reduce_min',
     'sequence_first_step', 'sequence_last_step', 'dropout', 'split',
-    'l2_normalize', 'matmul', 'warpctc'
+    'l2_normalize', 'matmul', 'warpctc', 'sequence_reshape'
 ]
 
 
@@ -213,33 +213,33 @@ def dynamic_lstm(input,
     (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) 
+        i_t & = \sigma(W_{ix}x_{t} + W_{ih}h_{t-1} + W_{ic}c_{t-1} + b_i)
 
-        \\tilde{c_t} & = act_g(W_{cx}x_t + W_{ch}h_{t-1} + b_c) 
+        f_t & = \sigma(W_{fx}x_{t} + W_{fh}h_{t-1} + W_{fc}c_{t-1} + b_f)
 
-        o_t & = \sigma(W_{ox}x_{t} + W_{oh}h_{t-1} + W_{oc}c_t + b_o) 
+        \\tilde{c_t} & = act_g(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} 
+        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 
+    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, 
+    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 :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
@@ -251,38 +251,38 @@ def dynamic_lstm(input,
     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 
+        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. 
+        param_attr(ParamAttr): The parameter attribute for the learnable
+                               hidden-hidden weights.
 
-                               - The shape is (D x 4D), where D is the hidden 
-                                 size. 
+                               - 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`. 
+                              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). 
+                              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). 
+                              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, 
+        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", 
+        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", 
+        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"],
@@ -1914,3 +1914,57 @@ def warpctc(input, label, blank=0, norm_by_times=False, **kwargs):
         attrs={'blank': blank,
                'norm_by_times': norm_by_times})
     return loss_out
+
+
+def sequence_reshape(input, new_dim):
+    """
+    **Sequence Reshape Layer**
+
+    This layer will rearrange the input sequences. The new dimension is set by
+    user. Length of each sequence is computed according to original length,
+    original dimension and new dimension. The following example will help to
+    illustrate the function of this layer:
+
+    .. code-block:: text
+
+        x is a LoDTensor:
+            x.lod  = [[0, 2, 6]]
+            x.data = [[1, 2], [3, 4],
+                      [5, 6], [7, 8], [9, 10], [11, 12]]
+            x.dims = [6, 2]
+
+        set new_dim = 4
+
+        then out is a LoDTensor:
+            out.lod  = [[0, 1, 3]]
+            out.data = [[1, 2, 3, 4],
+                        [5, 6, 7, 8], [9, 10, 11, 12]]
+            out.dims = [3, 4]
+
+    Currently, only 1-level LoDTensor is supported and please make sure
+    (original length * original dimension) can be divided by new dimension with
+    no remainder for each sequence.
+
+    Args:
+       input (Variable): (LodTensor, default: LoDTensor<float>), a 2-D LoDTensor
+                with shape being [N, M] where M for dimension.
+       new_dim (int): New dimension which the input LoDTensor is reshaped to.
+
+    Returns:
+        Variable: Reshaped LoDTensor according to new dimension.
+
+    Examples:
+        .. code-block:: python
+
+            x = fluid.layers.data(name='x', shape=[5, 20],
+                              dtype='float32', lod_level=1)
+            x_reshaped = layers.sequence_reshape(input=x, new_dim=10)
+    """
+    helper = LayerHelper('sequence_reshape', **locals())
+    out = helper.create_tmp_variable(helper.input_dtype())
+    helper.append_op(
+        type='sequence_reshape',
+        inputs={'X': [input]},
+        outputs={'Out': [out]},
+        attrs={'new_dim': new_dim})
+    return out

python/paddle/v2/fluid/tests/test_layers.py

@@ -216,6 +216,14 @@ def test_get_places(self):
             self.assertIsNotNone(x)
         print(str(program))
 
+    def test_sequence_reshape(self):
+        program = Program()
+        with program_guard(program):
+            x = layers.data(name='x', shape=[8], dtype='float32', lod_level=1)
+            out = layers.sequence_reshape(input=x, new_dim=16)
+            self.assertIsNotNone(out)
+        print(str(program))
+
 
 if __name__ == '__main__':
     unittest.main()