Compress and decompress with Blosc

Use the Blosc library to compress or decompress data.

Usage

blosc_compress(
  x,
  compressor = "blosclz",
  level = 7L,
  shuffle = "noshuffle",
  typesize = 4L,
  ...
)

blosc_decompress(x, ...)

Arguments

x

In case of blosc_decompress(), x should always be raw data to be decompressed. Use ... arguments to convert decompressed data to a specific data type.

In case of blosc_compress(), x should either be raw data or a vector of data to be compressed. In the latter case, you need to specify dtype (see r_to_dtype()) in order to convert the data to raw information first. See vignette("blosc-compression") for more details.

compressor

The compression algorithm to be used. Can be any of "blosclz", "lz4", "lz4hc", "zlib", or "zstd".

level

An integer indicating the required level of compression. Needs to be between 0 (no compression) and 9 (maximum compression).

shuffle

A shuffle filter to be activated before compression. Should be one of "noshuffle", "shuffle", or "bitshuffle".

typesize

BLOSC compresses arrays of structured data. This argument specifies the size (integer) of the data structure / type in bytes. Default is 4L bytes (i.e. 32 bits), which would be suitable for compressing 32 bit integers.

...

Arguments passed to r_to_dtype().

Value

In case of blosc_compress() a vector of compressed raw data is returned. In case of blosc_decompress() returns a vector of decompressed raw data. Or in in case dtype (see dtype_to_r()) is specified, a vector of the specified type is returned.

Examples

my_dat        <- as.raw(sample.int(2L, 10L*1024L, replace = TRUE) - 1L)
my_dat_out    <- blosc_compress(my_dat, typesize = 1L)
my_dat_decomp <- blosc_decompress(my_dat_out)

## After compressing and decompressing the data is the same as the original:
all(my_dat == my_dat_decomp)
#> [1] TRUE