Unexpected dependence on chunks with JSON and MsgPack codecs #258
Description
import numcodecs
import zarr
z = zarr.empty(1, dtype=object, object_codec=numcodecs.JSON(), chunks=(1,))
z[0] = ["11"]
print(z[:])
z[0] = ["11", "1"]
print(z[:]) # Borksgives
['11']
Traceback (most recent call last):
File "dev.py", line 204, in <module>
print(z[:])
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 555, in __getitem__
return self.get_basic_selection(selection, fields=fields)
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 681, in get_basic_selection
fields=fields)
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 723, in _get_basic_selection_nd
return self._get_selection(indexer=indexer, out=out, fields=fields)
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 1011, in _get_selection
drop_axes=indexer.drop_axes, fields=fields)
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 1604, in _chunk_getitem
chunk = self._decode_chunk(cdata)
File "/home/jk/.local/lib/python3.5/site-packages/zarr/core.py", line 1747, in _decode_chunk
chunk = chunk.reshape(self._chunks, order=self._order)
ValueError: cannot reshape array of size 2 into shape (1,)
Problem description
When using the JSON on MsgPack codecs to store an array of lists of strings, I get the above weird behaviour. It's easiest to just play around with the snippet above and try out different things, as it's tricky to explain what's happening. Basically though, it seems that this code path is sensitive to the chunk size in a way that others aren't --- typically, the library is perfectly happy with any chunk size.