BaseStore is missing

[jh85]

Zarr version

v3.0.6

Numcodecs version

v0.15.1

Python Version

3.12.3

Operating System

Linux

Installation

using pip

Description

I cannot create ZarrTrace object because "from zarr.storage import BaseStore" is failing in pymc/backends/zarr.py. What is the correct way to create a ZarrTrace object (I want to use it for pm.sample(trace=ZarrTrace object))?

Steps to reproduce

import zarr
from pymc.backends import ZarrTrace
zarr_trace = ZarrTrace("/home/xxx/temp.zarr")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/xxx/venv/lib/python3.12/site-packages/pymc/backends/zarr.py", line 356, in __init__
    raise RuntimeError("You must install zarr to be able to create ZarrTrace instances")
RuntimeError: You must install zarr to be able to create ZarrTrace instances

Additional output

No response

[jhamman]

It looks like PyMC has not made the jump to Zarr 3 yet. I suspect zarr==2.18.* should work for PyMC still.

@lucianopaz and @ricardoV94 - does PyMC have a tracking issue for zarr==3 support yet? Happy to provide some migration pointers.

[jh85]

Thank you. I downgraded zarr to 2.18 and it is working now.

from pymc.backends import ZarrTrace
zarr_trace = ZarrTrace("/home/xxx/temp.zarr")
zarr.__version__
'2.18.0'
pymc.__version__
5.22.0

[lucianopaz]

@jhamman, I'll open an issue over at PyMC to track upgrading to zarr>=3.x. At the moment, zarr is an optional dependency that's used for a very new feature that I'm trying to bring to pymc. When I started developing ZarrTrace, zarr 3 was still experimental, but I think that we won't have issues with migrating to the newer major version.

[lucianopaz]

@jhamman, I think that you can close this issue. It's not a zarr-python problem, it's a PyMC version requirement problem.