makeFileFormat {rtape}

Setting tape file format/compression.

Description

Setting tape file format/compression.

Usage

makeFileFormat(compression="gz", compressionLevel=ifelse(compression == "bz", 9, 6))

Arguments

compression

Name of the compression algorithm; should be one of the "gz", "bz", "xz". Exact name should be given. See connections for details.

compressionLevel

compression parameter passed to gzfile, bzfile or xzfile.

Details

rtape uses R connections to store data; this function creates a function that is used to create a connection by the other rtape's functions. Changing its parameters allows advanced user to change compression format/level and thus control the speed/file size trade-off. The default values (gzip, 6th level of compression) should give performance similar to this of save.

Value

The function to be passed to the fileFormat* arguments of other rtape's functions.

Note

Effectively, this function is needed only to set up the format of the new, blank tape (i.e. in the first call to rtapeAdd or for altering compression along with tape reconstruction operations performed by rtapeRerecord or rtapeFilter); when dealing with already existing tapes, the guessFileFormat will recognise the right format from the file header.

Author(s)

Miron B. Kursa [e-mail]