pydata / pydata/xarray

Composite operations on chunked array types not dispatched through chunk manager

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bug topic-arrays topic-chunked-arrays
Dominant language
Python
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Description

What happened?

The arkouda-xarray chunk manager (found here) is designed to allow Arkouda's distributed arrays to operate as chunked arrays in XArray. (Note Arkouda's array's also implement the array API, which was being used for XArray interoperability before the chunk manager was created).

When executing various operations on XArray DataArrays or DataSets that are backed by the Arkouda chunk manager, I noticed that they are not being routed through the chunk manager itself. For example, calling myArkoudaBackedArray.mean(axis="some-axis") does not get routed through ArkoudaManager.reduction. However, the operation is successful and produces the correct result, indicating that the array-api implementation of mean is being used instead (i.e., the arkouda-backed array is being treated as a duck array).

https://github.com/jeremiah-corrado/arkouda-xarray-seasonal-avgs-example/blob/main/README.md contains a full example where I observed the above behavior. It includes instructions to get Arkouda set up for XArray interoperability.

pinging @TomNicholas, since we discussed this the other day.

MVCE confirmation
  • Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
  • Complete example — the example is self-contained, including all data and the text of any traceback.
  • Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
  • New issue — a search of GitHub Issues suggests this is not a duplicate.
  • Recent environment — the issue occurs with the latest version of xarray and its dependencies.
Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None
python: 3.11.9 | packaged by conda-forge | (main, Apr 19 2024, 18:34:54) [Clang 16.0.6 ]
python-bits: 64
OS: Darwin
OS-release: 22.6.0
machine: arm64
processor: arm
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: ('en_US', 'UTF-8')
libhdf5: 1.12.2
libnetcdf: None

xarray: 2024.5.0
pandas: 2.2.2
numpy: 1.26.4
scipy: 1.13.1
netCDF4: None
pydap: None
h5netcdf: None
h5py: 3.8.0
zarr: None
cftime: 1.6.3
nc_time_axis: None
iris: None
bottleneck: None
dask: None
distributed: None
matplotlib: 3.8.4
cartopy: None
seaborn: None
numbagg: None
fsspec: None
cupy: None
pint: None
sparse: None
flox: None
numpy_groupies: None
setuptools: 70.0.0
pip: 24.0
conda: None
pytest: None
mypy: None
IPython: 8.24.0
sphinx: None

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with arkouda_xarray/arkoudamanager.py and the linked Arkouda seasonal-avgs example; reproduce mean(axis=...) on an Xarray object backed by the chunk manager. Trace why the call bypasses ArkoudaManager.reduction and instead uses the array-API path. Done when composite operations are routed through the chunk manager and the behavior is covered by regression tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
data, distributed-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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