fix tf version

Author: refraction-ray

requirements/requirements.txt

@@ -1,6 +1,6 @@
 numpy
 scipy
-tensorflow
+tensorflow<2.16 # tf 2.16 with integration of keras 3 seems a disaster...
 tensornetwork-ng
 graphviz
 jax

tensorcircuit/applications/ai/ensemble.py

@@ -3,6 +3,7 @@
 """
 
 from typing import Any, List, Optional
+from copy import deepcopy
 import tensorflow as tf
 import numpy as np
 
@@ -53,10 +54,12 @@ def train(self, **kwargs: kwargus) -> None:
 
     def compile(self, **kwargs: kwargus) -> None:
         self.permit_train = True
+
         for i in range(self.count):
             if not self.model_trained[i]:
                 dict_kwargs = kwargs.copy()
                 # TODO(@refraction-ray): still not compatible with new optimizer
+                # https://github.com/tensorflow/tensorflow/issues/58973
                 self.models[i].compile(**dict_kwargs)
 
     def __get_confidence(self, model_index: int, input: NDArray) -> NDArray:

tests/test_ensemble.py

@@ -2,6 +2,7 @@
 import sys
 import tensorflow as tf
 import numpy as np
+import pytest
 
 thisfile = os.path.abspath(__file__)
 modulepath = os.path.dirname(os.path.dirname(thisfile))
@@ -11,6 +12,9 @@
 from tensorcircuit.applications.ai.ensemble import bagging
 
 
+@pytest.mark.xfail(
+    int(tf.__version__.split(".")[1]) >= 16, reason="legacy optimizer fails tf>=2.16"
+)
 def test_ensemble_bagging():
     data_amount = 100  # Amount of data to be used
     linear_dimension = 4  # linear demension of the data