Copy in BitRound

[slevang]

I was benchmarking different compression options and realized BitRound was overwriting my array in place.

import shutil
import dask.array as da
from numcodecs import BitRound

def write_to_store(array, **kwargs):
    shutil.rmtree("test.zarr", ignore_errors=True)
    array.to_zarr("test.zarr", **kwargs)
    print(array.mean().compute())

array = da.random.default_rng(42).random((1,)).persist()

write_to_store(array)
write_to_store(array, filters=[BitRound(keepbits=5)])
write_to_store(array)

0.9167441575549085
0.921875
0.921875

Looks like there was discussion on this in the original PR but nothing came of it. Making an explicit copy seems to work fine as well, not sure which is preferred?

cc @rabernat

TODO:

• Unit tests and/or doctests in docstrings
• Tests pass locally
• Docstrings and API docs for any new/modified user-facing classes and functions
• Changes documented in docs/release.rst
• Docs build locally
• GitHub Actions CI passes
• Test coverage to 100% (Codecov passes)

[jakirkham]

Thanks Sam! 🙏

This is a good point to follow up

Would actually recommend just copying to start and then doing everything in-place on the copy. Otherwise we are generating a lot of temporary arrays

Mention this as we are doing compression memory usage can be an issue. So we want to reduce the amount of temporary arrays we create if possible

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.91%. Comparing base (85eb7aa) to head (0ea5164).
Report is 56 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #608   +/-   ##
=======================================
  Coverage   99.91%   99.91%           
=======================================
  Files          59       59           
  Lines        2327     2328    +1     
=======================================
+ Hits         2325     2326    +1     
  Misses          2        2           

Files with missing lines	Coverage Δ
numcodecs/bitround.py	100.00% <100.00%> (ø)

[jakirkham]

Thanks Sam! 🙏

[jakirkham]

Release note is in PR: #609