QGAN functionality request

[J-Mertl]

Hi,

I'm trying to implement a QGAN in qiskit version 2.1. However, all tutorials I've found are for Version 0.8 and earlier - like on Kaggle or qiskit.
Now obviously some functionalities have been moved or removed for good reason - I however can't figure out why in 'qiskit_machine_learning.datasets' all functionalities but 'ad_hoc' got removed (e.g. the 'dataset_helper' seems quite useful). I also couldn't find any good git-commit message explaining why it was removed.

Thanks for your help.

P.S.: I'm mainly trying to convert the Kaggle implementation right now, which fails due to the missing 'discretize_and_truncate' function from the dataset_helper. Additionally, I've noticed the 'CircuitQNN' from 'qiskit_machine_learning.neural_networks' being removed or moved, but I haven't looked into this to far yet.

[edoaltamura]

Datasets like iris or wine can be sourced from Scikit-Learn (already a dependency), so having them in Qiskit ML would be redundant. This isn't true for ad_hoc, which is specific to quantum ML.

This thread might be useful to get more context: #330 (comment).

We also plan to expand ad_hoc and add a few quantum-only datasets, like in #915.

[J-Mertl]

I see, that makes sense then
Thanks

[J-Mertl]

So I progressed a bit on the QGAN implementation - and now I'm facing issues with the torch_connector (importing "BaseEstimator" which should now be "EstimatorV2" I think), when will this approximately be updated for compatability of qiskit version 2?

[edoaltamura]

With Qiskit 1.4.3 or lower, it should return a deprecation warning, but not an error. With Qiskit 2+, instead, it will fail indeed because V1 primitives are removed. We found that many users still prefer to use V1 primitives, so we decided to support both V1 and V2 at least until later this year (at the cost of pinning Qiskit to 1.4).
Then, we plan to do as you suggest - to remove V1s and enable compatibility with Qiskit 2+. Most of the progress towards this is captured in https://github.com/qiskit-community/qiskit-machine-learning/milestone/5.