Expectation value w.r.t. qreg list

[Zoufalc]

What is the expected enhancement?

Allow expectation value evaluation circuit generation w.r.t. to a list of qregs instead of a single qreg only

In the WeightedPauliOperator line 643, 644 the following check is conducted
if not wave_function.has_register(qr):
raise AquaError("The provided QuantumRegister (qr) is not in the circuit.")
This prevents to construct the evaluation circuits w.r.t. a list of qregs/qubits. e.g. [q0[0], q0[2], q1[1]]. The rest of the function works with this kind of list though.

[dongreenberg]

Hi Christa - #852 gets rid of using specific qregs for the expectation, and instead allows you to just append your expectation measurement to the circuit directly. Does this solve your issue?

[Zoufalc]

Hey Donny,
If I can specify the qubits to append the expectation measurement to - which I assume - yes.

[woodsp-ibm]

Christa, from discussion with Donny, and above comments, I understand with the new operator flow and the use now of the new expectation objects that your needs should be accommodated. As such I am closing this.