bug with setitem with oindex and sharding

[dcherian]

Zarr version

v3.0.2

Numcodecs version

?

Python Version

3.12

Operating System

any

Installation

any

Description

Discovered in #2825

Steps to reproduce

import zarr
import numpy as np

store = zarr.storage.MemoryStore()
group = zarr.group(store)
array = group.create_array(
    name="zoo",
    shape=(1,2,1),
    chunks=(1,2,1),
    shards=(1,2,1),
    dtype=np.int32,
)
zindexer = (np.array([0]), np.array([0, 0]), np.array([0]))
new_data = np.full(array.oindex[zindexer].shape, fill_value=1)
array.oindex[zindexer] = new_data

raises the error:

ValueError: shape mismatch: value array of shape (1,2,1) could not be broadcast to indexing result of shape (2,)

It succeeds with shards=None.

Additional output

No response

[brokkoli71]

I think the problem is that the information that the selection is an OrthogonalSelection gets lost on the way.

In ShardingCodec._encode_partial_single a new indexer is created to index the inner chunks:

indexer = list(
    get_indexer(
        selection, shape=shard_shape, chunk_grid=RegularChunkGrid(chunk_shape=chunk_shape)
    )
)

There, get_indexer guesses what indexing should be done based on the selection tuple, and in this case guesses CoordinateIndexer instead of OrthogonalIndexer