Issue/78/sacc

[Lhior]

QP/SACC interface #78

There was no direct way to move redshift distributions n(z) between qp Ensemble format (typical for RAIL pipelines) and sacc.Sacc format (used in cosmology analyses and PriorSacc). Based heavily on Jaime's nz_prior example.

Solution

Implemented sacc_tools with RailStage converters and helpers:

• QPToSACC – Converts n(z) from qp Ensemble files (one per tomographic bin) to a single sacc.Sacc catalog with QPNZ tracers. Supports optional truth files and flexible input (list of paths or {tracer_name: file_path}).
• SACCToQP – Converts n(z) from a sacc catalog back to qp Ensemble files on disk, one per QPNZ tracer.
• normalize_hist() – Normalizes histogram PDFs so they integrate to 1.
• extract_tomographic_bins_from_sacc() – Extracts a tomographic bin structure from sacc catalogs.
• Demo notebook (sacc_qp_interface_demo.ipynb) – Round-trip workflow using gold-baseline data provided by @eacharles during the Princeton sprint week. I think bin 0 is a little buggy from previous talks with Eric but can't remember if the culprit was identified (plotting script or the data file itself)
• Unit tests (tests/astro_tools/test_sacc_tools.py) – 26 tests for all public APIs.
• Dependencies – Added qp-prob>=1.0 and sacc>=2.1 to pyproject.toml.

Code Quality

• [✅] My code follows the code style of this project
• [✅] I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• [✅] My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• [N/A?] Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[eacharles]

These changes look good, but could you update your branch to the main.

[eacharles]

Sorry. I didn't see this until now.

[eacharles]

Looks good. Please just rebase your branch against main before merging.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.87%. Comparing base (4a656d6) to head (0c40a66).

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #91      +/-   ##
===========================================
- Coverage   100.00%   99.87%   -0.13%     
===========================================
  Files           15       16       +1     
  Lines         1447     1662     +215     
===========================================
+ Hits          1447     1660     +213     
- Misses           0        2       +2     

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