CosmoStat / CosmoStat/shapepipe
ngmix mcal_flags records nothing when metacal fails wholesale
Nobody has claimed this yet.
- Dominant language
- Python
- Stars
- 18
- Forks
- 14
- Avg merge
- 8h 40m
- Merged PRs (30d)
- 10
Description
Found during the A/B characterization campaign (#813): when a missing library feature made every object's metacal fit fail silently (sentinel outputs, no exception), the catalogue came out fully populated with mcal_flags == 0 throughout — the failure was only visible by inspecting sentinel values by hand.
Root cause: both get_mcal_flags and the mcal_types_fail counter default an absent result (or missing 'flags' key) to 0 — success. Absence of evidence of success is treated as success. A fitter that lies about succeeding (flags 0, non-finite shear) is also never caught, and there is no aggregate guard for the 100%-failure case.
— Claude (Fable), on behalf of Cail.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating get_mcal_flags and the mcal_types_fail counter, then trace how absent results, missing 'flags', and non-finite shear are handled. Reproduce the wholesale metacal failure described in the issue and verify that it is no longer recorded as successful, including an aggregate check for the 100%-failure case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100