The change ensures that the elements are packed back into the original structure in the correct order by using keys derived from the structure's flattened paths.

tensorflow_model_optimization/python/core/internal/tensor_encoding/core/simple_encoder.py

@@ -134,7 +134,12 @@ def decode_fn(encoded_structure):
       encoded_structure = py_utils.merge_dicts(encoded_structure,
                                                encoded_py_structure['flat_py'])
       encoded_structure = tf.nest.pack_sequence_as(
-          encoded_py_structure['full'], tf.nest.flatten(encoded_structure))
+          encoded_py_structure['full'],
+          [
+              encoded_structure[k] for k, _ in
+              py_utils.flatten_with_joined_string_paths(
+                  encoded_py_structure['full'])
+          ])
       return encoder.decode(encoded_structure[_TENSORS],
                             encoded_structure[_PARAMS],
                             encoded_structure[_SHAPES])

tensorflow_model_optimization/python/core/internal/tensor_encoding/core/simple_encoder_test.py

@@ -141,6 +141,35 @@ def test_python_constants_not_exposed(self):
     self.assertAllClose(x, decoded_x_tf)
     self.assertAllClose(x, decoded_x_py)
 
+  @tf_test_util.run_all_in_graph_and_eager_modes
+  def test_interleaved_py_tf_parameters(self):
+    """Tests that interleaved Python and TF parameters are decoded correctly."""
+    class SwappedKeysStage(test_utils.SimpleLinearEncodingStage):
+      def get_params(self, name=None):
+        # Return parameters in a specific order to test if encoding/decoding
+        # respects this order or sorts keys.
+        params = {self.B_PARAM_KEY: self._b, self.A_PARAM_KEY: self._a}
+        return params, params
+
+    x = tf.constant(2.0)
+    tensorspec = tf.TensorSpec.from_tensor(x)
+
+    # Use one Python constant and one TF Variable to ensure they are split and merged.
+    b_var = tf.compat.v1.get_variable('b_var_interleaved', initializer=3.0)
+
+    encoder = simple_encoder.SimpleEncoder(
+        core_encoder.EncoderComposer(
+            SwappedKeysStage(2.0, b_var)).make(),
+        tensorspec)
+
+    state = encoder.initial_state()
+    iteration = _make_iteration_function(encoder)
+
+    self.evaluate(tf.compat.v1.global_variables_initializer())
+
+    x_val, _, decoded_x, _ = self.evaluate(iteration(x, state))
+    self.assertAllClose(x_val, decoded_x)
+
   @tf_test_util.run_all_in_graph_and_eager_modes
   def test_decode_needs_input_shape_static(self):
     """Tests that mechanism for passing input shape works with static shape."""