Merge pull request #6609 from kuke/fix_reshape_op

Enable reshape_op to support dimension inference

paddle/operators/reshape_op.cc

@@ -34,21 +34,33 @@ class ReshapeOp : public framework::OperatorWithKernel {
     auto shape = ctx->Attrs().Get<std::vector<int>>("shape");
     PADDLE_ENFORCE(shape.size() > 0, "Attr(shape) shouldn't be empty.");
     auto x_dims = ctx->GetInputDim("X");
-    // TODO(qiao) change batch_size
-    for (size_t i = 1; i < shape.size(); ++i) {
-      PADDLE_ENFORCE(shape[i] > 0,
-                     "Each dimension of Attr(shape) "
-                     "must be positive except the first one.");
-    }
-    if (shape[0] < 0) {
-      shape[0] = x_dims[0];
+
+    std::vector<size_t> neg_dims_idx;
+    // set some dimension to -1 if it is unknown
+    const int unknown_size = -1;
+    for (size_t i = 0; i < shape.size(); ++i) {
+      PADDLE_ENFORCE(shape[i] > 0 || shape[i] == unknown_size,
+                     "Each dimension of Attr(shape) must be positive or %d.",
+                     unknown_size);
+      if (shape[i] == unknown_size) {
+        neg_dims_idx.push_back(i);
+        PADDLE_ENFORCE(neg_dims_idx.size() <= 1,
+                       "Only one dimension of Attr(shape) can be unknown.");
+      }
     }
-    // capacity check
+
     int64_t capacity =
         std::accumulate(shape.begin(), shape.end(), 1, std::multiplies<int>());
     int64_t in_size = framework::product(x_dims);
-    PADDLE_ENFORCE_EQ(capacity, in_size,
-                      "The size of Input(X) mismatches with Attr(shape).");
+    if (neg_dims_idx.size() == 1) {
+      // dim infer
+      shape[neg_dims_idx[0]] = in_size / (-capacity);
+      // recalculate capacity
+      capacity = shape[neg_dims_idx[0]] * (-capacity);
+    }
+    // capacity check
+    PADDLE_ENFORCE(capacity == in_size,
+                   "The size of Input(X) mismatches with Attr(shape).");
     // resize output
     std::vector<int64_t> shape_int64(shape.size(), 0);
     std::transform(shape.begin(), shape.end(), shape_int64.begin(),
@@ -88,6 +100,9 @@ the tensor X into a 2-D tensor:
 
     [[1, 2, 3, 4]]
 
+One dimension in the target shape can be set -1, representing that its
+size is unknown. In this case, the real dimension will be infered from 
+the original shape of Input(X) and other dimensions in the target shape.
 )DOC");
   }
 };

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

@@ -17,5 +17,19 @@ class TestReshapeOp(OpTest):
         self.check_grad(["X"], "Out")
 
 
+class TestReshapeOpDimInfer(OpTest):
+    def setUp(self):
+        self.op_type = "reshape"
+        self.inputs = {'X': np.random.random((10, 20)).astype("float32")}
+        self.attrs = {'shape': [4, -1, 5]}
+        self.outputs = {'Out': self.inputs['X'].reshape(self.attrs['shape'])}
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad(self):
+        self.check_grad(["X"], "Out")
+
+
 if __name__ == '__main__':
     unittest.main()