Contents

0.1 Zarr version

Rarr supports both Zarr version 2 and Zarr version 3.

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 Stores

Store Type Status
(reading / writing)		 Notes
FilesystemStore ✔ / ✔
S3Store ✔ / ❌ Read more in the S3 vignette

0.2.2 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 ✔ / ✔ (via {grumpy})
int8 ✔ / ✔ (via {grumpy})
uint8 ✔ / ✔ (via {grumpy})
int16 ✔ / ✔ (via {grumpy})
uint16 ✔ / ✔ (via {grumpy})
int32 ✔ / ✔ (via {grumpy})
uint32 ✔ / ✔ (via {grumpy})
int64 ✔ / ✔ (via {grumpy})
uint64 ✔ / ✔ (via {grumpy})
half / float16 ✔ / ❌ (via {grumpy})
single / float32 ✔ / ✔ (via {grumpy})
double / float64 ✔ / ✔ (via {grumpy})
bfloat16 ✔ / ❌
complex ❌ / ❌
timedelta ❌ / ❌
datetime ❌ / ❌
V2 string ✔ / ✔ (via {grumpy})
V3 null_terminated_bytes ✔ / ✔ (via {grumpy})
V2 Unicode ✔ / ✔ (via {grumpy})
V3 fixed_length_utf32 ✔ / ✔ (via {grumpy})
void * ❌ / ❌
V2 structured data types ✔ / ❌ (via {grumpy})
V3 structured data types ✔ / ❌ This type is superseded by V3 struct data types.and the specification says implementation MUST NOT implement writing. (via {grumpy})
V3 struct data types ✔ / ❌ (via {grumpy})

Scalars can only be written via update_zarr_array(). write_zarr_array() requires x to be an array so it can only write arrays with a single dimensions of length 1 (which behave mostly like a scalar in R).

0.2.3 Codecs

0.2.3.1 Compression codecs

Library Status
(reading / writing)		 Notes
zlib / gzip ✔ / ✔
bzip2 ✔ / ✔
blosc ✔ / ✔
LZMA ✔ / ✔
LZ4 ✔ / ✔
Zstd ✔ / ✔

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

0.2.3.2 Other codecs

Codec Status
(reading / writing)		 Notes
endian ✔ / ❌ (via {grumpy})
transpose ✔ / ✔
VLen-UTF8 ✔ / ✔ * Through using the data_type = "string" argument in write_zarr_array()
sharding_indexed ✔ / ❌

0.2.4 Optional fields or features

Feature Status
(reading / writing)		 Notes
dimension_names ✔ / ✔ Corresponds to names(dimnames(x)) in R