Adapter keeps track of the transform jacobians

[Kucharssim]

fixes #245

I have not implemented it for NumpyTransform because I was not sure about implementation w.r.t. serialization. I tried to make sure that if we cannot keep track of the jacobians, we raise an error rather than returning an incorrect output.

[codecov]

Codecov Report

Attention: Patch coverage is 88.80597% with 15 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
bayesflow/approximators/continuous_approximator.py	0.00%	4 Missing ⚠️
bayesflow/adapters/transforms/filter_transform.py	85.00%	3 Missing ⚠️
bayesflow/adapters/transforms/map_transform.py	86.95%	3 Missing ⚠️
bayesflow/adapters/transforms/drop.py	50.00%	1 Missing ⚠️
...sflow/adapters/transforms/elementwise_transform.py	50.00%	1 Missing ⚠️
bayesflow/adapters/transforms/keep.py	50.00%	1 Missing ⚠️
bayesflow/adapters/transforms/numpy_transform.py	50.00%	1 Missing ⚠️
bayesflow/adapters/transforms/transform.py	50.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
bayesflow/adapters/adapter.py	82.77% <100.00%> (+1.14%)	⬆️
bayesflow/adapters/transforms/concatenate.py	87.69% <100.00%> (+3.37%)	⬆️
bayesflow/adapters/transforms/constrain.py	83.49% <100.00%> (+16.82%)	⬆️
bayesflow/adapters/transforms/log.py	100.00% <100.00%> (ø)
bayesflow/adapters/transforms/rename.py	93.33% <100.00%> (+0.47%)	⬆️
bayesflow/adapters/transforms/scale.py	100.00% <100.00%> (ø)
bayesflow/adapters/transforms/sqrt.py	93.75% <100.00%> (+2.84%)	⬆️
bayesflow/adapters/transforms/standardize.py	97.67% <100.00%> (+0.37%)	⬆️
bayesflow/adapters/transforms/drop.py	88.23% <50.00%> (-5.10%)	⬇️
...sflow/adapters/transforms/elementwise_transform.py	78.94% <50.00%> (-3.41%)	⬇️
... and 6 more

[LarsKue]

Thanks for the PR. Could you add tests for this behavior @Kucharssim? See e.g., tests/test_networks/test_inference_networks.py::test_density_numerically for a related test.

[Kucharssim]

Yes, on it!

[LarsKue]

This was accidentally closed. We will investigate how to restore the branch and reopen PRs.

[LarsKue]

Thank you for implementing this! I noted some minor concerns, mostly regarding clarity.

[LarsKue]

Thank you for the changes! I think we are mostly ready to merge this as-is. Can you address the open conversation above and the comments from Copilot? Thanks!

[Copilot]

Pull Request Overview

This PR enhances the adapter functionality by adding support for tracking the log determinant of the Jacobians across transforms. Key changes include:

• Introducing log_det_jac methods for several transforms (e.g. standardize, sqrt, scale, constrain, etc.).
• Modifying the adapter’s forward and inverse methods to optionally return the log determinant of the Jacobian.
• Adding comprehensive tests to verify the correct computation and exception handling for the Jacobian tracking.

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/test_adapters/test_adapters.py	Updated tests to cover additional keys and jacobian tracking tests.
tests/test_adapters/conftest.py	Introduced new fixtures that test the log_det_jac functionality.
bayesflow/approximators/continuous_approximator.py	Modified forward method to incorporate and apply the change‐of‐variables formula.
bayesflow/adapters/transforms/*	Added or updated log_det_jac methods across multiple transform files.
bayesflow/adapters/adapter.py	Updated forward and inverse methods to support the log_det_jac flag.

[Kucharssim]

Ok, I think I addressed everything now. If you are happy with this, feel free to merge