Contents

0.1 Zarr version

Support for Zarr version 3 is actively being worked on, and some features are likely to be missing.

It is currently known that reading only is supported, not writing, and that the sharding codec is not supported.

0.2 Reading and Writing

Reading Zarr arrays is reasonably well supported. Writing is available, but is more limited. Both aspects are under active development.

0.2.1 Data Types

Currently there is only support for reading and writing a subset of the possible datatypes that can be found in a Zarr array. In some instances there are also limitations on the datatypes natively supported by R, requiring conversion from the Zarr datatype. The table below summarises the current status of datatype support. It will be updated as progress is made.

Zarr Data Type Status
(reading / writing)		 Notes
boolean ✔ / ✔
int8 ✔ / ❌
uint8 ✔ / ✔
int16 ✔ / ✔
uint16 ✔ / ❌
int32 ✔ / ✔
uint32 ✔ / ❌ Values outside the range of int32 are converted to NA. Future plan is to allow conversion to double or use the bit64 package.
int64 ✔ / ❌ Values outside the range of int32 are converted to NA. Future plan is to allow conversion to double or use the bit64 package.
uint64 ✔ / ❌ Values outside the range of int32 are converted to NA. Future plan is to allow conversion to double or use the bit64 package.
half / float16 ✔ / ❌ Converted to double in R. No effort is made to assess loss of precision due to conversion.
single / float32 ✔ / ✔ Converted to double in R. No effort is made to assess loss of precision due to conversion.
double / float64 ✔ / ✔
complex ❌ / ❌
timedelta ❌ / ❌
datetime ❌ / ❌
string ✔ / ✔
Unicode ✔ / ✔
void * ❌ / ❌
Structured data types ❌ / ❌

0.2.2 Codecs

0.2.2.1 Compression codecs

Data Type Status
(reading / writing)		 Notes
zlib / gzip ✔ / ✔ Only system default compression level (normally 6) is enabled for writing.
bzip2 ✔ / ✔ Only compression level 9 is enabled for writing.
blosc ✔ / ✔ Only lz4 compression level 5 is enabled for writing.
LZMA ✔ / ✔
LZ4 ✔ / ✔
Zstd ✔ / ✔

Please open an issue if support for a required compression codec is missing.

0.2.2.2 Other codecs

Codec Status
(reading / writing)		 Notes
endian ✔ / ❌
transpose ✔ / ✔ Only the simple T/C case defined in v2