refine annotation

paddle/gserver/layers/SequenceLastInstanceLayer.cpp

@@ -26,8 +26,10 @@ namespace paddle {
  * If SequenceLevel = kNonseq:
  *   Output: a sequence containing only the last instance of the input sequence
  *   If stride_ > 0:
- *      Output: a shorten sequence containing several last instances of the
- *              input sequence with stride window.
+ *      Output: a shorten sequence. The operation of getting last instance of a
+ *              sequence is independently performed on every slice of the input
+ *              sequence, which is obtained by sliding a window with the window
+ *              size set to stride_.
  * If SequenceLevel = kSeq:
  *   Check input sequence must has sub-sequence
  *   Output: a sequence containing only the last instance of each sub-sequence

paddle/gserver/layers/SequencePoolLayer.h

@@ -27,9 +27,9 @@ namespace paddle {
  *    output[i] = seqlastin/average/max_{for each instance in this
  * sequence}{input[i]}
  *    If stride_ > 0:
- *        Check input sequence must don't have sub-sequence
+ *        Check input sequence must not have sub-sequence
  *        Output: a shorten sequence, pooling is performed upon a small local
- * area
+ *                area
  * If SequenceLevel = kSeq:
  *    Check input sequence must has sub-sequence
  *    Output: output size is the number of input sub-sequences
@@ -47,9 +47,9 @@ protected:
   size_t newBatchSize_;
   ICpuGpuVectorPtr startPositions_;
   int stride_;
-  // store the start position of each stride window
+  // store the start position of each window
   IVectorPtr stridePositions_;
-  // Whether it is reversed sequence
+  // Whether the input sequence is reversed or not
   bool reversed_ = false;
 
 public:

paddle/parameter/Argument.cpp

@@ -589,7 +589,7 @@ void Argument::poolSequenceWithStride(const Argument& input,
     } else {
       int size = ceil((float)seqLength / stride);
       tgtBuf[seqId + 1] = tgtBuf[seqId] + size;
-      for (int i = 0; i < size - 1; i++) {
+      for (int i = 0; i < size - 1; ++i) {
         int cur = reversed ? starts[seqId + 1] - (size - 1 - i) * stride
                            : stridePos.back() + stride;
         stridePos.emplace_back(cur);

paddle/parameter/Argument.h

@@ -294,7 +294,7 @@ struct Argument {
   /*
    After pooling with stride n (n is smaller than sequence length),
    a long sequence will be shorten.
-   This function is not suitable for sequence with sub-sequence now.
+   This function is invalid for sequence having sub-sequence.
    */
   void poolSequenceWithStride(const Argument& input,
                               size_t stride,

python/paddle/trainer_config_helpers/layers.py

@@ -1347,9 +1347,10 @@ def last_seq(input,
     """
     Get Last Timestamp Activation of a sequence.
 
-    If stride > 0, get last timestamp upon a stride window of sequence. 
-    And a long sequence will be shorten. Note that for sequence with 
-    sub-sequence, stride is default -1 now.
+    If stride > 0, this layer slides a window whose size is determined by stride, 
+    and return the last value of the window as the output. Thus, a long sequence 
+    will be shorten. Note that for sequence with sub-sequence, the default value 
+    of stride is -1.
 
     The simple usage is:
 
@@ -1362,7 +1363,7 @@ def last_seq(input,
     :type name: basestring
     :param input: Input layer name.
     :type input: LayerOutput
-    :param stride: parameter of stride window.  
+    :param stride: window size.  
     :type stride: Int
     :param layer_attr: extra layer attributes.
     :type layer_attr: ExtraLayerAttribute.
@@ -1402,9 +1403,10 @@ def first_seq(input,
     """
     Get First Timestamp Activation of a sequence.
 
-    If stride > 0, get first timestamp upon a stride window of sequence,
-    and a long sequence will be shorten. Note that for sequence with 
-    sub-sequence, stride is default -1 now.
+    If stride > 0, this layer slides a window whose size is determined by stride, 
+    and return the first value of the window as the output. Thus, a long sequence 
+    will be shorten. Note that for sequence with sub-sequence, the default value 
+    of stride is -1.
 
     The simple usage is:
 
@@ -1417,7 +1419,7 @@ def first_seq(input,
     :type name: basestring
     :param input: Input layer name.
     :type input: LayerOutput
-    :param stride: parameter of stride window.  
+    :param stride: window size.  
     :type stride: Int
     :param layer_attr: extra layer attributes.
     :type layer_attr: ExtraLayerAttribute.