add SequenceConcatLayer in trainer_config_helpers

paddle/gserver/layers/SequenceConcatLayer.cpp

@@ -21,9 +21,11 @@ namespace paddle {
 
 /**
  * A layer for concatenating the first sequence with the second sequence
- * following the first
+ * Input: two sequences each containing the same number of instances
- * Input: two sequences each containing some instances
+ *        seq1 = [a1, a2, ..., an]
+ *        seq2 = [b1, b2, ..., bn]
  * Output: a concatenated sequence of the two input sequences
+ *        out = [a1, b1, a2, b2, ..., an, bn]
  */
 
 class SequenceConcatLayer : public Layer {

python/paddle/trainer_config_helpers/layers.py

@@ -59,6 +59,7 @@ __all__ = [
     'img_cmrnorm_layer',
     'addto_layer',
     'concat_layer',
+    'seq_concat_layer',
     'lstm_step_layer',
     'recurrent_group',
     'memory',
@@ -144,6 +145,7 @@ class LayerType(object):
 
     CONCAT_LAYER = 'concat'
     CONCAT_PROJ_LAYER = 'concat2'
+    SEQUENCE_CONCAT_LAYER = 'seqconcat'
 
     LSTM_STEP_LAYER = 'lstm_step'
     GRU_STEP_LAYER = 'gru_step'
@@ -2570,6 +2572,55 @@ def concat_layer(input, act=None, name=None, layer_attr=None, bias_attr=None):
         size=sz)
 
 
+@wrap_name_default("seqconcat")
+@wrap_act_default(act=IdentityActivation())
+@layer_support()
+def seq_concat_layer(a, b, act=None, name=None, layer_attr=None,
+                     bias_attr=None):
+    """
+    Concat sequence a with sequence b.
+    Inputs: a = [a1, a2, ..., an]
+            b = [b1, b2, ..., bn]
+            Note that the length of a and b should be the same.
+    Output: [a1, b1, a2, b2, ..., an, bn]
+
+    The example usage is:
+
+    ..  code-block:: python
+
+        concat = seq_concat_layer(a=layer1, b=layer2)
+
+    :param name: Layer name.
+    :type name: basestring
+    :param a: input sequence layer
+    :type a: LayerOutput
+    :param b: input sequence layer
+    :type b: LayerOutput
+    :param act: Activation type.
+    :type act: BaseActivation
+    :param layer_attr: Extra Layer Attribute.
+    :type layer_attr: ExtraLayerAttribute
+    :return: LayerOutput object.
+    :rtype: LayerOutput
+    """
+    assert isinstance(a, LayerOutput) and isinstance(b, LayerOutput)
+    assert a.size == b.size
+    Layer(
+        name=name,
+        type=LayerType.SEQUENCE_CONCAT_LAYER,
+        inputs=[a.name, b.name],
+        active_type=act.name,
+        bias=ParamAttr.to_bias(bias_attr),
+        **ExtraLayerAttribute.to_kwargs(layer_attr))
+
+    return LayerOutput(
+        name,
+        layer_type=LayerType.SEQUENCE_CONCAT_LAYER,
+        parents=[a, b],
+        activation=act,
+        size=a.size)
+
+
 def memory(name,
            size,
            is_seq=False,

python/paddle/trainer_config_helpers/tests/configs/file_list.sh

@@ -4,6 +4,7 @@ test_sequence_pooling test_lstmemory_layer test_grumemory_layer
 last_first_seq test_expand_layer test_ntm_layers test_hsigmoid
 img_layers img_trans_layers util_layers simple_rnn_layers unused_layers test_cost_layers
 test_rnn_group shared_fc shared_lstm shared_gru test_cost_layers_with_weight
-test_spp_layer test_bilinear_interp test_maxout test_bi_grumemory math_ops)
+test_spp_layer test_bilinear_interp test_maxout test_bi_grumemory math_ops
+test_seq_concat)
 
 export whole_configs=(test_split_datasource)

python/paddle/trainer_config_helpers/tests/configs/protostr/test_seq_concat.protostr

@@ -0,0 +1,39 @@
+type: "nn"
+layers {
+  name: "data1"
+  type: "data"
+  size: 30
+  active_type: ""
+}
+layers {
+  name: "data2"
+  type: "data"
+  size: 30
+  active_type: ""
+}
+layers {
+  name: "__seqconcat_0__"
+  type: "seqconcat"
+  size: 30
+  active_type: ""
+  inputs {
+    input_layer_name: "data1"
+  }
+  inputs {
+    input_layer_name: "data2"
+  }
+}
+input_layer_names: "data1"
+input_layer_names: "data2"
+output_layer_names: "__seqconcat_0__"
+sub_models {
+  name: "root"
+  layer_names: "data1"
+  layer_names: "data2"
+  layer_names: "__seqconcat_0__"
+  input_layer_names: "data1"
+  input_layer_names: "data2"
+  output_layer_names: "__seqconcat_0__"
+  is_recurrent_layer_group: false
+}
+

python/paddle/trainer_config_helpers/tests/configs/test_seq_concat.py

@@ -0,0 +1,9 @@
+from paddle.trainer_config_helpers import *
+
+settings(batch_size=1000, learning_rate=1e-5)
+
+din1 = data_layer(name='data1', size=30)
+
+din2 = data_layer(name='data2', size=30)
+
+outputs(seq_concat_layer(a=din1, b=din2))