uncompress: Uncompress in-memory data in either zlib or GNU zip format
In statwonk/Rcompression: In-memory decompression for GNU zip and bzip2 formats.

Description Usage Arguments Value Author(s) References See Also Examples

These functions take a “raw” vector in R that contains data that is compressed via some algorithm and attempts to inflate/uncompress the data so it can be processed directly with other tools. These function support the basic zlib algorithm, GNU zip format and bunzip2-style compression. The difference between these and functions such as gzcon is that these work with data already in memory, not in files. These are also currently not connections.

uncompress(content, size = length(content) * 10, asText = TRUE,
            resizeBy = 2)
gunzip(content, size = length(content) * 5, asText = TRUE)
bunzip2(content, size = length(content) * 5, verbose = 0, asText = TRUE)

`content`	the “raw” vector in R that contains the entire stream of compressed data.
`size`	a value that guesses how big the resulting inflated contents will be. This is used to create a buffer that will hold the results. If this is not sufficiently large, the buffer will be expanded so it is not vital that this be correct. However, getting it about right and a little bigger than the actual resulting size of the inflated content will make the processing faster and not waste excess memory.
`verbose`	an integer between 0 and 4 inclusive with larger values indicating to display more information on the console about the inflation process as it is being performed. 0 means no information.
`asText`	a logical value indicating whether to return the result as a simple R string (`TRUE`) or leave it uninterpreted as a `raw` vector. `FALSE` is appropriate if the uncompressed contents are binary data.
`resizeBy`	the factor by which the internal memory buffer used to store the uncompressed data is grown when more memory is needed. The default is to double the size. In the worst case, this might mean needing one more byte to complete the de-compression, but asking for `2 * (total_length - 1)`. This parameter allows the caller to provide a way to control this expansion with contextual knowledge.

The inflated contents either as a string or a raw vector.

Duncan Temple Lang

zlib and bzip2

compress

 x = "A string to compress"
 g = compress(x)
 uncompress(g) == x

 # Read contents of a GNU zipped file and uncompress the contents
 # directly from memory.  We could do this with gz() directly from R
 # but this is just arranging to get the raw data locally rather than,
 # e.g. from an HTTP request

 f = system.file("sampleData", "NAMESPACE.gz", package = "Rcompression")
 con = file(f, "rb")
 fs = file.info(f)$size
 content  = readBin(con, raw(fs), fs)
 close(con)
 gunzip(content, 10000)