NeuralNetworkClassifier save error

[prncoprs]

Environment

• Qiskit Machine Learning version: 0.6.0
• Python version: 3.11.2
• Operating system: MacOS 13.3.1

What is happening?

When I run the 11_quantum_convolutional_neural_networks.ipynb to learn, I want to save the classifier model, and I run the following code.

classifier.save("qcnn.classifier")

However, it will produce following error logs.

Traceback (most recent call last):
  File "/Users/xxx/Projects/iu/qaml-qiskit/qcnn.py", line 246, in <module>
    classifier.save("qcnn.classifier")
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/qiskit_machine_learning/algorithms/serializable_model.py", line 36, in save
    dill.dump(self, handler)
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 336, in dump
    Pickler(file, protocol, **_kwds).dump(obj)
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 620, in dump
    StockPickler.dump(self, obj)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 487, in dump
    self.save(obj)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 603, in save
    self.save_reduce(obj=obj, *rv)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 717, in save_reduce
    save(state)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
    ^^^^^^^^^^^^
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 1251, in save_module_dict
    StockPickler.save_dict(pickler, obj)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 972, in save_dict
    self._batch_setitems(obj.items())
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 998, in _batch_setitems
    save(v)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
    ^^^^^^^^^^^^
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 1963, in save_function
    _save_with_postproc(pickler, (_create_function, (
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 1140, in _save_with_postproc
    pickler.save_reduce(*reduction, obj=obj)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 692, in save_reduce
    save(args)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
    ^^^^^^^^^^^^
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 902, in save_tuple
    save(element)
  File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
    ^^^^^^^^^^^^
  File "/Users/xxx/Projects/iu/qaml-qiskit/venv/lib/python3.11/site-packages/dill/_dill.py", line 1187, in save_code
    obj.co_firstlineno, obj.co_lnotab, obj.co_endlinetable,
                                       ^^^^^^^^^^^^^^^^^^^
AttributeError: 'code' object has no attribute 'co_endlinetable'. Did you mean: 'co_linetable'?

Process finished with exit code 1

How can we reproduce the issue?

Run the code in 11_quantum_convolutional_neural_networks.ipynb](https://github.com/Qiskit/qiskit-machine-learning/blob/main/docs/tutorials/11_quantum_convolutional_neural_networks.ipynb), and try to save the model using following code.

classifier.save("qcnn.classifier")

What should happen?

The classifier should be saved into a file.

Any suggestions?

No response

[woodsp-ibm]

What version of dill are you using. I believe that was a 3.11 issue in dill that was corrected in their 0.3.6 release.

Note that Qiskit ML does not yet officially support 3.11 #512

I will also note dill was pinned here earlier #498 so installing 0.3.6 would conflict with that in your installation. Can you use an earlier Python e.g. 3.10?

[prncoprs]

Thanks for your help! I changed to 3.10 and it works!