Merge pull request #12971 from sneaxiy/unstack_op

Add unstack op

Author: sneaxiy

paddle/fluid/API.spec

@@ -164,6 +164,7 @@ paddle.fluid.layers.prelu ArgSpec(args=['x', 'mode', 'param_attr', 'name'], vara
 paddle.fluid.layers.flatten ArgSpec(args=['x', 'axis', 'name'], varargs=None, keywords=None, defaults=(1, None))
 paddle.fluid.layers.sequence_mask ArgSpec(args=['x', 'maxlen', 'dtype', 'name'], varargs=None, keywords=None, defaults=(None, 'int64', None))
 paddle.fluid.layers.stack ArgSpec(args=['x', 'axis'], varargs=None, keywords=None, defaults=(0,))
+paddle.fluid.layers.unstack ArgSpec(args=['x', 'axis', 'num'], varargs=None, keywords=None, defaults=(0, None))
 paddle.fluid.layers.data ArgSpec(args=['name', 'shape', 'append_batch_size', 'dtype', 'lod_level', 'type', 'stop_gradient'], varargs=None, keywords=None, defaults=(True, 'float32', 0, VarType.LOD_TENSOR, True))
 paddle.fluid.layers.open_recordio_file ArgSpec(args=['filename', 'shapes', 'lod_levels', 'dtypes', 'pass_num', 'for_parallel'], varargs=None, keywords=None, defaults=(1, True))
 paddle.fluid.layers.open_files ArgSpec(args=['filenames', 'shapes', 'lod_levels', 'dtypes', 'thread_num', 'buffer_size', 'pass_num', 'is_test'], varargs=None, keywords=None, defaults=(None, None, 1, None))

paddle/fluid/operators/CMakeLists.txt

@@ -291,6 +291,7 @@ op_library(unsqueeze_op DEPS reshape_op)
 op_library(squeeze_op DEPS reshape_op)
 op_library(extract_rows_op DEPS memory)
 op_library(flatten_op DEPS reshape_op)
+op_library(unstack_op DEPS stack_op)
 
 if (WITH_GPU)
     op_library(conv_op DEPS vol2col depthwise_conv im2col)

paddle/fluid/operators/unstack_op.cc

@@ -0,0 +1,26 @@
+// Copyright (c) 2018 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.
+
+#include "paddle/fluid/operators/unstack_op.h"
+
+namespace plat = paddle::platform;
+namespace ops = paddle::operators;
+
+USE_OP(stack);
+
+REGISTER_OPERATOR(unstack, ops::UnStackOp, ops::UnStackOpMaker,
+                  ops::UnStackOpInferShape, ops::UnStackGradOpDescMaker);
+
+REGISTER_OPERATOR(unstack_grad, ops::UnStackGradOp,
+                  ops::UnStackOpGradInferShape);

paddle/fluid/operators/unstack_op.h

@@ -0,0 +1,135 @@
+// Copyright (c) 2018 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.
+
+#pragma once
+
+#include "paddle/fluid/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+class UnStackOpInferShape : public framework::InferShapeBase {
+ public:
+  void operator()(framework::InferShapeContext *ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("X"), "Input(X) must exist.");
+
+    int axis = ctx->Attrs().Get<int>("axis");
+    int num = ctx->Attrs().Get<int>("num");
+    auto x_dim = ctx->GetInputDim("X");
+    int rank = x_dim.size();
+    PADDLE_ENFORCE(axis >= -rank && axis < rank,
+                   "Attr(axis) must be inside [-rank, rank), where rank = %d",
+                   rank);
+    if (axis < 0) axis += rank;
+
+    PADDLE_ENFORCE_EQ(ctx->Outputs("Y").size(), static_cast<size_t>(num),
+                      "Number of Outputs(Y) is wrong");
+    if (x_dim[axis] > 0) {
+      PADDLE_ENFORCE_EQ(num, x_dim[axis], "Number of Outputs(Y) is wrong");
+    }
+    auto vec = framework::vectorize2int(x_dim);
+    vec.erase(vec.begin() + axis);
+    ctx->SetOutputsDim("Y", std::vector<framework::DDim>(  // NOLINT
+                                x_dim[axis], framework::make_ddim(vec)));
+  }
+};
+
+class UnStackOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  void Make() override {
+    AddInput("X", "The input of unstack op.");
+    AddOutput("Y", "The output of unstack op.").AsDuplicable();
+    AddAttr<int>("axis", "The axis along which Input(X) should be unstacked.")
+        .SetDefault(0);
+    AddAttr<int>("num", "The number of outputs(Y).").GreaterThan(0);
+    AddComment(R"DOC(
+      UnStack Operator.
+
+      UnStack Input(X) into several tensors along Attr(axis).
+    )DOC");
+  }
+};
+
+class UnStackOp : public framework::OperatorBase {
+ public:
+  using OperatorBase::OperatorBase;
+
+ private:
+  void RunImpl(const framework::Scope &scope,
+               const platform::Place &place) const override {
+    auto stack_grad_op = framework::OpRegistry::CreateOp(
+        "stack_grad", {{framework::GradVarName("Y"), {Input("X")}}},
+        {{framework::GradVarName("X"), Outputs("Y")}}, Attrs());
+    stack_grad_op->Run(scope, place);
+  }
+};
+
+class UnStackOpGradInferShape : public framework::InferShapeBase {
+ public:
+  void operator()(framework::InferShapeContext *ctx) const override {
+    PADDLE_ENFORCE_GT(ctx->Inputs(framework::GradVarName("Y")).size(), 0,
+                      "Number of Inputs(Y@Grad) must be larger than 0");
+    PADDLE_ENFORCE(ctx->HasOutput(framework::GradVarName("X")),
+                   "Output(X@Grad) must exist.");
+
+    auto input_dims = ctx->GetInputsDim(framework::GradVarName("Y"));
+    for (size_t i = 1; i < input_dims.size(); ++i) {
+      PADDLE_ENFORCE_EQ(input_dims[i], input_dims[0],
+                        "Dims of all Inputs(Y@Grad) must be the same");
+    }
+
+    int axis = ctx->Attrs().Get<int>("axis");
+    int rank = input_dims[0].size();
+    PADDLE_ENFORCE(
+        axis >= -(rank + 1) && axis < rank + 1,
+        "Attr(axis) must be inside [-(rank+1), rank+1), where rank = %d", rank);
+    if (axis < 0) axis += (rank + 1);
+
+    auto vec = framework::vectorize2int(input_dims[0]);
+    vec.insert(vec.begin() + axis, input_dims.size());
+    ctx->SetOutputDim(framework::GradVarName("X"), framework::make_ddim(vec));
+  }
+};
+
+class UnStackGradOpDescMaker : public framework::SingleGradOpDescMaker {
+ public:
+  using framework::SingleGradOpDescMaker::SingleGradOpDescMaker;
+
+ protected:
+  std::unique_ptr<framework::OpDesc> Apply() const override {
+    std::unique_ptr<framework::OpDesc> op(new framework::OpDesc());
+    op->SetType("unstack_grad");
+    op->SetInput(framework::GradVarName("Y"), OutputGrad("Y"));
+    op->SetOutput(framework::GradVarName("X"), InputGrad("X"));
+    op->SetAttrMap(Attrs());
+    return op;
+  }
+};
+
+class UnStackGradOp : public framework::OperatorBase {
+ public:
+  using OperatorBase::OperatorBase;
+
+ private:
+  void RunImpl(const framework::Scope &scope,
+               const platform::Place &place) const override {
+    auto stack_op = framework::OpRegistry::CreateOp(
+        "stack", {{"X", Inputs(framework::GradVarName("Y"))}},
+        {{"Y", {Output(framework::GradVarName("X"))}}}, Attrs());
+    stack_op->Run(scope, place);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

python/paddle/fluid/layers/nn.py

@@ -105,6 +105,7 @@
     'flatten',
     'sequence_mask',
     'stack',
+    'unstack',
 ]
 
 
@@ -5601,3 +5602,44 @@ def stack(x, axis=0):
         type='stack', inputs={'X': x}, outputs={'Y': out},
         attrs={'axis': axis})
     return out
+
+
+def unstack(x, axis=0, num=None):
+    """
+    **UnStack Layer**
+
+    This layer unstacks input :code:`x` into several tensors along axis.
+   
+    If :code:`axis` < 0, it would be replaced with :code:`axis+rank(x)`.
+    If :code:`num` is None, it would be inferred from :code:`x.shape[axis]`,
+    and if :code:`x.shape[axis]` <= 0 or is unknown, :code:`ValueError` is
+    raised. 
+
+    Args:
+        x (Variable): Input variable. 
+        axis (int): The axis along which the input is unstacked.
+        num (int|None): The number of output variables.
+    
+    Returns:
+        list(Variable): The unstacked variables.
+    
+    """
+
+    helper = LayerHelper('unstack', **locals())
+    if num is None:
+        if axis is None or x.shape[axis] <= 0:
+            raise ValueError('unknown unstack number')
+        else:
+            num = x.shape[axis]
+
+    outs = []
+    for _ in num:
+        outs.append(helper.create_tmp_variable(x.dtype))
+
+    helper.append_op(
+        type='unstack',
+        inputs={'X': [x]},
+        outputs={'Y': outs},
+        attrs={'axis': axis,
+               'num': num})
+    return outs

python/paddle/fluid/tests/unittests/test_unstack_op.py

@@ -0,0 +1,81 @@
+# Copyright (c) 2018 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.
+
+from op_test import OpTest
+import numpy as np
+import unittest
+
+
+class TestUnStackOpBase(OpTest):
+    def initDefaultParameters(self):
+        self.input_dim = (5, 6, 7)
+        self.axis = 0
+        self.dtype = 'float32'
+
+    def initParameters(self):
+        pass
+
+    def get_y_names(self):
+        y_names = []
+        for i in range(self.input_dim[self.axis]):
+            y_names.append('y{}'.format(i))
+        return y_names
+
+    def setUp(self):
+        self.initDefaultParameters()
+        self.initParameters()
+        self.op_type = 'unstack'
+        self.x = np.random.random(size=self.input_dim).astype(self.dtype)
+
+        outs = np.split(self.x, self.input_dim[self.axis], self.axis)
+        new_shape = list(self.input_dim)
+        del new_shape[self.axis]
+        y_names = self.get_y_names()
+        tmp = []
+        for i in range(self.input_dim[self.axis]):
+            tmp.append((y_names[i], np.reshape(outs[i], new_shape)))
+
+        self.inputs = {'X': self.x}
+        self.outputs = {'Y': tmp}
+        self.attrs = {'axis': self.axis, 'num': self.input_dim[self.axis]}
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad(self):
+        self.check_grad('X', self.get_y_names())
+
+
+class TestStackOp3(TestUnStackOpBase):
+    def initParameters(self):
+        self.axis = -1
+
+
+class TestStackOp4(TestUnStackOpBase):
+    def initParameters(self):
+        self.axis = -3
+
+
+class TestStackOp5(TestUnStackOpBase):
+    def initParameters(self):
+        self.axis = 1
+
+
+class TestStackOp6(TestUnStackOpBase):
+    def initParameters(self):
+        self.axis = 2
+
+
+if __name__ == '__main__':
+    unittest.main()