Roll forward of more robust Network Input conformance.

PiperOrigin-RevId: 297470882
Change-Id: Ic78cbd2448cf3c28282ebadcb4491096f0d38c3f

tensorflow/python/keras/engine/network.py

@@ -51,6 +51,7 @@ from tensorflow.python.keras.utils import generic_utils
 from tensorflow.python.keras.utils import layer_utils
 from tensorflow.python.keras.utils import tf_utils
 from tensorflow.python.keras.utils.io_utils import ask_to_proceed_with_overwrite
+from tensorflow.python.ops import array_ops
 from tensorflow.python.ops import math_ops
 from tensorflow.python.ops.ragged import ragged_tensor
 from tensorflow.python.platform import tf_logging as logging
@@ -238,6 +239,9 @@ class Network(base_layer.Layer):
       outputs = outputs[0]
     self._nested_outputs = outputs
     self._nested_inputs = inputs
+    self._nested_inputs_are_flat_list = (
+        isinstance(self._nested_inputs, (list, tuple)) and
+        not any(nest.is_sequence(t) for t in self._nested_inputs))
     self.inputs = nest.flatten(inputs)
     self.outputs = nest.flatten(outputs)
 
@@ -814,40 +818,18 @@ class Network(base_layer.Layer):
     # use masking, it does not interfere with regular behavior at all and you
     # can ignore it.
 
-    if isinstance(inputs, dict) and isinstance(self._nested_inputs,
-                                               (list, tuple)):
-      # Backwards compat: Allows passing a dict to a Model constructed with a
-      # list. Matches dict keys to input names.
-      inputs = [
-          inputs[inp._keras_history.layer.name] for inp in self._nested_inputs
-      ]
-    else:
-      inputs = nest.flatten(inputs)
-
+    inputs = self._flatten_to_reference_inputs(inputs)
     if mask is None:
       masks = [None for _ in range(len(inputs))]
     else:
-      masks = nest.flatten(mask)
-
+      masks = self._flatten_to_reference_inputs(mask)
     for input_t, mask in zip(inputs, masks):
       input_t._keras_mask = mask
 
     # Dictionary mapping reference tensors to computed tensors.
     tensor_dict = {}
-
     for x, y in zip(self.inputs, inputs):
-      # Set shape and dtype based on `keras.Input`s.
-      if isinstance(x, ops.Tensor) and isinstance(y, ops.Tensor):
-        try:
-          y.set_shape(y.shape.merge_with(x.shape))
-        except ValueError:
-          logging.warning(
-              'Model was constructed with shape {} for input {}, but it was '
-              're-called on a Tensor with incompatible shape {}.'
-              .format(x, x.shape, y.shape))
-      if isinstance(x, (ops.Tensor, composite_tensor.CompositeTensor)):
-        y = math_ops.cast(y, dtype=x.dtype)
-
+      y = self._conform_to_reference_input(y, ref_input=x)
       x_id = str(id(x))
       tensor_dict[x_id] = [y] * self._tensor_usage_count[x_id]
 
@@ -925,6 +907,53 @@ class Network(base_layer.Layer):
     output_tensors = nest.pack_sequence_as(self._nested_outputs, output_tensors)
     return output_tensors
 
+  def _flatten_to_reference_inputs(self, tensors):
+    """Maps `tensors` to their respective `keras.Input`."""
+    if self._nested_inputs_are_flat_list and isinstance(tensors, dict):
+      # Backwards compat: Allows passing a dict to a Model constructed with a
+      # list. Matches dict keys to input names.
+      tensors = [
+          tensors[inp._keras_history.layer.name] for inp in self._nested_inputs
+      ]
+    else:
+      # Otherwise both self.inputs and tensors will be flattened in same order.
+      tensors = nest.flatten(tensors)
+    return tensors
+
+  def _conform_to_reference_input(self, tensor, ref_input):
+    """Set shape and dtype based on `keras.Input`s."""
+    # Shape handling (only for non-CompositeTensors).
+    if isinstance(tensor, ops.Tensor) and isinstance(ref_input, ops.Tensor):
+      # Allow (None,) and (None, 1) Tensors to be passed interchangably. Use the
+      # shape specified by the `keras.Input`.
+      if tensor.shape.rank is not None and ref_input.shape.rank is not None:
+        should_squeeze_last_dim = (
+            tensor.shape.rank == ref_input.shape.rank + 1 and
+            tensor.shape[-1] == 1)
+        should_expand_last_dim = (
+            tensor.shape.rank == ref_input.shape.rank - 1 and
+            ref_input.shape[-1] == 1)
+        if should_squeeze_last_dim:
+          tensor = array_ops.squeeze_v2(tensor, axis=-1)
+        elif should_expand_last_dim:
+          tensor = array_ops.expand_dims_v2(tensor, axis=-1)
+
+      # Add shape hints to Tensors that might have None shape dims but have
+      # shapes defined by the `keras.Input`.
+      try:
+        tensor.set_shape(tensor.shape.merge_with(ref_input.shape))
+      except ValueError:
+        logging.warning(
+            'Model was constructed with shape {} for input {}, but it was '
+            'called on an input with incompatible shape {}.'.format(
+                ref_input.shape, ref_input, tensor.shape))
+
+    # Dtype handling.
+    if isinstance(ref_input, (ops.Tensor, composite_tensor.CompositeTensor)):
+      tensor = math_ops.cast(tensor, dtype=ref_input.dtype)
+
+    return tensor
+
   def get_config(self):
     if not self._is_graph_network:
       raise NotImplementedError

tensorflow/python/keras/engine/network_test.py

@@ -1879,6 +1879,24 @@ class CacheCorrectnessTest(keras_parameterized.TestCase):
     for i in range(999, 1024):
       self.assertEqual(network.compute_output_shape((1, i, 32)), (1, i, 2))
 
+  def test_2d_inputs_squeezed_to_1d(self):
+    input_1d = input_layer_lib.Input(shape=())
+    outputs = input_1d * 2.
+    net = network_lib.Network(input_1d, outputs)
+
+    x = np.ones((10, 1))
+    y = net(x)
+    self.assertEqual(y.shape.rank, 1)
+
+  def test_1d_inputs_expanded_to_2d(self):
+    input_1d = input_layer_lib.Input(shape=(1,))
+    outputs = input_1d * 2.
+    net = network_lib.Network(input_1d, outputs)
+
+    x = np.ones((10,))
+    y = net(x)
+    self.assertEqual(y.shape.rank, 2)
+
 
 if __name__ == '__main__':
   test.main()