QNSPSA function optimize not implemented

[Christophe-pere]

Environment

• Qiskit Algorithms version: 0.3.0
• Python version: 3.10.9
• Operating system: Linux

What is happening?

Hi,

I want to use the optimizer QNSPSA. I used the documentation on the github page. I used the sample code in the description of the class

            import numpy as np
            from qiskit_algorithms.optimizers import QNSPSA
            from qiskit.circuit.library import PauliTwoDesign
            from qiskit.primitives import Estimator, Sampler
            from qiskit.quantum_info import Pauli

            # problem setup
            ansatz = PauliTwoDesign(2, reps=1, seed=2)
            observable = Pauli("ZZ")
            initial_point = np.random.random(ansatz.num_parameters)

            # loss function
            estimator = Estimator()

            def loss(x):
                result = estimator.run([ansatz], [observable], [x]).result()
                return np.real(result.values[0])

            # fidelity for estimation of the geometric tensor
            sampler = Sampler()
            fidelity = QNSPSA.get_fidelity(ansatz, sampler)

            # run QN-SPSA
            qnspsa = QNSPSA(fidelity, maxiter=300)
            result = qnspsa.optimize(ansatz.num_parameters, loss, initial_point=initial_point)

And, surprise... I got the error AttributeError: 'QNSPSA' object has no attribute 'optimize' because optimize is not implemented...

How can we reproduce the issue?

Simply run the code provided in the class description.

What should happen?

Optimization process.

Any suggestions?

Complete the class with the optimize function or update the documentation and class description in order to have a good reference to use the optimizer.