add is empty op (#5639)

paddle/operators/is_empty_op.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   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/framework/op_registry.h"
+#include "paddle/framework/operator.h"
+
+namespace paddle {
+namespace operators {
+
+constexpr char kInput[] = "X";
+constexpr char kOutput[] = "Out";
+
+class IsEmptyOp : public framework::OperatorBase {
+ public:
+  IsEmptyOp(const std::string &type, const framework::VariableNameMap &inputs,
+            const framework::VariableNameMap &outputs,
+            const framework::AttributeMap &attrs)
+      : OperatorBase(type, inputs, outputs, attrs) {}
+
+  void Run(const framework::Scope &scope,
+           const platform::DeviceContext &dev_ctx) const override {
+    // get input
+    auto *var = scope.FindVar(Input(kInput));
+    PADDLE_ENFORCE_NOT_NULL(var);
+    auto &tensor = var->Get<framework::LoDTensor>();
+    // get output
+    auto *out = scope.FindVar(Output(kOutput));
+    PADDLE_ENFORCE_NOT_NULL(out);
+    auto *out_tensor = out->GetMutable<framework::LoDTensor>();
+
+    out_tensor->Resize({1});
+    out_tensor->mutable_data<bool>(platform::CPUPlace())[0] =
+        framework::product(tensor.dims()) == 0;
+  }
+};
+
+class IsEmptyOpProtoMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  IsEmptyOpProtoMaker(framework::OpProto *proto,
+                      framework::OpAttrChecker *op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddInput(kInput, "(Tensor) Tensor which is to be checked.");
+    AddOutput(kOutput, "(Tensor) a boolean Tensor that indicate empty or not.");
+    AddComment(R"DOC(
+IsEmpty Operator which checks whether a tensor is empty.
+
+It will just return product(tensor.ddims()) > 0;
+              )DOC");
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+REGISTER_OP_WITHOUT_GRADIENT(is_empty, paddle::operators::IsEmptyOp,
+                             paddle::operators::IsEmptyOpProtoMaker);

python/paddle/v2/framework/tests/test_is_empty_op.py

+import unittest
+import numpy as np
+from paddle.v2.framework.op import Operator
+import paddle.v2.framework.core as core
+
+
+def create_tensor(scope, name, np_data):
+    tensor = scope.var(name).get_tensor()
+    tensor.set_dims(np_data.shape)
+    tensor.set(np_data, core.CPUPlace())
+    return tensor
+
+
+class TestIsEmptyOp(unittest.TestCase):
+    def setUp(self):
+        self.scope = core.Scope()
+        # create input variables
+        np_data0 = np.array([0, 1, 2])
+        create_tensor(self.scope, "X0", np_data0)
+
+        np_data1 = np.array([1])
+        t = create_tensor(self.scope, "X1", np_data1)
+        t.set_dims([0])
+
+        # create output variables
+        self.scope.var("out")
+
+    def test_no_empty(self):
+        self.one_case("X0", False)
+
+    def test_empty(self):
+        self.one_case("X1", True)
+
+    def one_case(self, input, target):
+        op = Operator(type="is_empty", X=input, Out="out")
+        ctx = core.DeviceContext.create(core.CPUPlace())
+        op.run(self.scope, ctx)
+        out = self.scope.var("out").get_tensor()
+        self.assertEqual(np.array(out)[0], target)
+
+
+if __name__ == "__main__":
+    unittest.main()