When reading a Zarr array using read_zarr_array() it is necessary to know
it's shape and size. zarr_overview() can be used to get a quick overview of
the array shape and contents, based on the .zarray (Zarr v2) or zarr.json
(Zarr v3) metadata file each array contains.
Arguments
- zarr_array_path
A character vector of length 1. This provides the path to a Zarr array or group of arrays. This can either be on a local file system or on S3 storage.
- s3_client
A list representing an S3 client. This should be produced by
paws.storage::s3().- as_data_frame
Logical determining whether the Zarr array details should be printed to screen (
FALSE) or returned as adata.frame(TRUE) so they can be used computationally.
Value
If as_data_frame = FALSE the function invisible returns TRUE if
successful. However it is primarily called for the side effect of printing
details of the Zarr array(s) to the screen. If as_data_frame = TRUE then
a data.frame containing details of the array is returned.
Details
The function currently prints the following information to the R console:
array path
array shape and size
chunk and size
the number of chunks
the datatype of the array
codec used for data compression (if any)
If given the path to a group of arrays the function will attempt to print the details of all sub-arrays in the group.
Examples
## Using a local file provided with the package
z1 <- system.file("extdata", "zarr_examples", "row-first",
"int32.zarr",
package = "Rarr"
)
## read the entire array
zarr_overview(zarr_array_path = z1)
#> Type: Array
#> Path: /home/runner/work/_temp/Library/Rarr/extdata/zarr_examples/row-first/int32.zarr
#> Shape: 30 x 20 x 10
#> Chunk Shape: 10 x 10 x 5
#> No. of Chunks: 12 (3 x 2 x 2)
#> Data Type: int32
#> Endianness: little
#> Compressor: blosc
## using a file on S3 storage
# \donttest{
z2 <- "https://noaa-nwm-retro-v2-zarr-pds.s3.amazonaws.com/feature_id/"
zarr_overview(z2)
#> Type: Array
#> Path: https://noaa-nwm-retro-v2-zarr-pds.s3.amazonaws.com/feature_id
#> Shape: 2729077
#> Chunk Shape: 2729077
#> No. of Chunks: 1 (1)
#> Data Type: int32
#> Endianness: little
#> Compressor: blosc
# }