Fix bug: shapes of Topk outputs are wrong when the parameter k is Tensor

Fix bug: shapes of Topk outputs are wrong when the parameter k is Tensor 

paddle/fluid/operators/top_k_v2_op.cc

@@ -32,7 +32,6 @@ class TopkV2Op : public framework::OperatorWithKernel {
 
     auto input_dims = ctx->GetInputDim("X");
     const int& dim_size = input_dims.size();
-    const int k = static_cast<int>(ctx->Attrs().Get<int>("k"));
     int axis = static_cast<int>(ctx->Attrs().Get<int>("axis"));
     PADDLE_ENFORCE_EQ((axis < dim_size) && (axis >= (-1 * dim_size)), true,
                       "the axis of topk"
@@ -41,8 +40,18 @@ class TopkV2Op : public framework::OperatorWithKernel {
 
     if (axis < 0) axis += dim_size;
 
-    PADDLE_ENFORCE_GE(
-        k, 1, "the attribute of k in the topk must >= 1, but received %d .", k);
+    int k;
+    auto k_is_tensor = ctx->HasInput("K");
+    if (k_is_tensor) {
+      k = -1;
+    } else {
+      k = static_cast<int>(ctx->Attrs().Get<int>("k"));
+      PADDLE_ENFORCE_EQ(k >= 1, true,
+                        "the attribute of k in the topk must >= 1 or be a "
+                        "Tensor, but received %d .",
+                        k);
+    }
+
     PADDLE_ENFORCE_GE(input_dims.size(), 1,
                       "input of topk must have >= 1d shape");
 

python/paddle/fluid/tests/unittests/test_top_k_v2_op.py

@@ -63,28 +63,28 @@ class TestTopkOp(OpTest):
         self.check_grad(set(['X']), 'Out')
 
 
-class TestTopOp1(TestTopkOp):
+class TestTopkOp1(TestTopkOp):
     def init_args(self):
         self.k = 3
         self.axis = 0
         self.largest = True
 
 
-class TestTopOp2(TestTopkOp):
+class TestTopkOp2(TestTopkOp):
     def init_args(self):
         self.k = 3
         self.axis = 0
         self.largest = False
 
 
-class TestTopOp3(TestTopkOp):
+class TestTopkOp3(TestTopkOp):
     def init_args(self):
         self.k = 4
         self.axis = 0
         self.largest = False
 
 
-class TestTopOp4(TestTopkOp):
+class TestTopkOp4(TestTopkOp):
     def init_args(self):
         self.k = 4
         self.axis = 0
@@ -189,6 +189,8 @@ class TestTopKAPI(unittest.TestCase):
             result1 = paddle.topk(input_tensor, k=2)
             result2 = paddle.topk(input_tensor, k=2, axis=-1)
             result3 = paddle.topk(input_tensor, k=k_tensor, axis=1)
+            self.assertEqual(result3[0].shape, (6, -1, 8))
+            self.assertEqual(result3[1].shape, (6, -1, 8))
             result4 = paddle.topk(input_tensor, k=2, axis=1, largest=False)
             result5 = paddle.topk(input_tensor, k=2, axis=-1, largest=False)
             result6 = paddle.topk(large_input_tensor, k=1, axis=-1)
@@ -239,6 +241,15 @@ class TestTopKAPI(unittest.TestCase):
             self.run_dygraph(place)
             self.run_static(place)
 
+    def test_errors(self):
+        paddle.disable_static()
+        x = paddle.to_tensor([1, 2, 3])
+        with self.assertRaises(BaseException):
+            paddle.topk(x, k=-1)
+
+        with self.assertRaises(BaseException):
+            paddle.topk(x, k=0)
+
 
 if __name__ == "__main__":
     unittest.main()