Merge pull request PaddlePaddle#4094 from lcy-seso/fix_cross_entropy_op_output_shape

fix shape of output tensor of cross_entropy_op.

Author: lcy-seso

paddle/operators/cross_entropy_op.cc

@@ -29,7 +29,7 @@ class OnehotCrossEntropyOp : public framework::OperatorWithKernel {
     PADDLE_ENFORCE_EQ(X->dims().size(), 2, "X's dimension must be 2.");
     PADDLE_ENFORCE_EQ(label->dims().size(), 1, "label's dimension must be 1.");
     PADDLE_ENFORCE_EQ(X->dims()[0], label->dims()[0]);
-    ctx.Output<Tensor>("Y")->Resize({X->dims()[0]});
+    ctx.Output<Tensor>("Y")->Resize({X->dims()[0], 1});
   }
 };
 

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

@@ -8,20 +8,22 @@ def setUp(self):
         self.op_type = "onehot_cross_entropy"
         batch_size = 30
         class_num = 10
+
         X = numpy.random.uniform(0.1, 1.0,
                                  [batch_size, class_num]).astype("float32")
-        label = (class_num / 2) * numpy.ones(batch_size).astype("int32")
-        self.inputs = {'X': X, 'label': label}
-        Y = []
-        for i in range(0, batch_size):
-            Y.append(-numpy.log(X[i][label[i]]))
-        self.outputs = {'Y': numpy.array(Y).astype("float32")}
+        labels = numpy.random.randint(0, class_num, batch_size, dtype="int32")
+
+        cross_entropy = numpy.asmatrix(
+            [[-numpy.log(X[i][labels[i]])] for i in range(X.shape[0])],
+            dtype="float32")
+        self.inputs = {"X": X, "label": labels}
+        self.outputs = {"Y": cross_entropy}
 
     def test_check_output(self):
         self.check_output()
 
     def test_check_grad(self):
-        self.check_grad(['X'], 'Y')
+        self.check_grad(["X"], "Y")
 
 
 if __name__ == "__main__":