update sequence slice op, fix some error

paddle/operators/sequence_slice_op.cc

@@ -75,14 +75,17 @@ class SequenceSliceOpMaker : public framework::OpProtoAndCheckerMaker {
              "the input of SequenceSliceOp.");
     AddInput("Offset",
              "(Tensor), "
-             "A vector<int> to describes offset for sub sequence item.");
+             "a vector<int> to describe the offset of every input sequence for "
+             "sub sequence item.");
     AddInput("Length",
              "(Tensor), "
-             "A vector<int> to describes length for sub sequence item.");
+             "a vector<int> to describe the length of every input sequence for "
+             "sub sequence item.");
     AddOutput("Out",
-              "(LoDTensor), output of sequence slice Op.");
+              "(LoDTensor), The output of SequenceSliceOp.");
     AddComment(R"DOC(
 Sequence slice operator
+
 The operator crop a subsequence from given sequence with given start offset and subsequence length.
 It only supports sequence (LoD Tensor with level number is 1).
 - Case:
@@ -91,13 +94,13 @@ It only supports sequence (LoD Tensor with level number is 1).
         c1, c2]
        [d1, d2;
         e1, e2]]
-    LoD(X) = {{0, 3, 5}}; Dims(X) = (4, 1, 2)
-    Offset = (0, 1); Length = (2, 1)
+    LoD(X) = {{0, 3, 5}}; Dims(X) = (5, 2)
+    Offset = [0, 1]; Length = [2, 1]
 
     Out = [[a1, a2;
             b1, b2]
             [e1, e2]]
-    LoD(Out) = {{0, 2, 3}}
+    LoD(Out) = {{0, 2, 3}}; Dims(Out) = (3, 2)
 NOTE: The length of the input, offset and length should be the same. The offset start from 0.
     )DOC");
   }

paddle/operators/sequence_slice_op.h

@@ -87,9 +87,10 @@ class SequenceSliceOpKernel : public framework::OpKernel<T> {
 
     out->mutable_data<T>(ctx.GetPlace());
     auto out_lod = SequenceSliceLoD(*in, offset_data, length_data);
+    auto out_dims = in->dims();
+    out_dims[0] = out_lod[0][out_lod[0].size() - 1];
+    out->Resize(out_dims);
     out->set_lod(out_lod);
-    math::SetConstant<Place, T> set_zero;
-    set_zero(ctx.device_context(), out, static_cast<T>(0));
 
     auto in_stride = framework::stride(in->dims());
     auto out_stride = framework::stride(out->dims());

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

@@ -5,25 +5,32 @@ from op_test import OpTest
 
 class TestSequenceSliceOp(OpTest):
     def set_data(self):
+        self.init_test_case()
         # only supprot one level LoD
-        x = np.random.random((100, 3, 2)).astype('float32')
-        lod = [[0, 20, 40, 60, 80, 100]]
-        offset = np.array([1, 2, 3, 4, 5]).flatten().astype("int64")
-        length = np.array([10, 8, 6, 4, 2]).flatten().astype("int64")
+        x = np.random.random(self.x_dim).astype('float32')
+        lod = self.x_lod
+        offset = np.array(self.offset).flatten().astype("int64")
+        length = np.array(self.length).flatten().astype("int64")
 
         self.inputs = {'X': (x, lod), 'Offset': offset, 'Length': length}
-        outs = np.zeros((100, 3, 2)).astype('float32')
+        outs = [] #np.zeros((100, 3, 2)).astype('float32')
         out_lod = [[0]]
         out_lod_offset = 0
         for i in range(len(offset)):
             sub_x = x[lod[0][i] + offset[i]: lod[0]
                       [i] + offset[i] + length[i], :]
             out_lod_offset = out_lod_offset + len(sub_x)
-            outs[out_lod[0][i]: out_lod_offset, :] = sub_x
+            outs.append(sub_x)
             out_lod[0].append(out_lod_offset)
-
+        outs = np.concatenate(outs, axis=0)
         self.outputs = {'Out': (outs, out_lod)}
 
+    def init_test_case(self):
+        self.x_dim = (100, 3, 2)
+        self.x_lod = [[0, 20, 40, 60, 80, 100]]
+        self.offset = [1, 2, 3, 4, 5]
+        self.length = [10, 8, 6, 4, 2]
+
     def setUp(self):
         self.op_type = "sequence_slice"
         self.set_data()