compressFile: Compressing and decompressing files

In R.utils: Various Programming Utilities

Compressing and decompressing files

Description

Compressing and decompressing files such as gzip:ed and bzip2:ed files.

NOTE: The default (remove=TRUE) behavior is that the input file is removed after that the output file is fully created and closed.

Usage

 ## Default S3 method:
compressFile(filename, destname=sprintf("%s.%s", filename, ext), ext, FUN,
  temporary=FALSE, skip=FALSE, overwrite=FALSE, remove=TRUE, BFR.SIZE=1e+07, ...)
 ## Default S3 method:
decompressFile(filename, destname=gsub(sprintf("[.]%s$", ext), "", filename,
  ignore.case = TRUE), ext, FUN, temporary=FALSE, skip=FALSE, overwrite=FALSE,
  remove=TRUE, BFR.SIZE=1e+07, ...)
 ## Default S3 method:
isCompressedFile(filename, method=c("extension", "content"), ext, fileClass, ...)
 ## Default S3 method:
bzip2(filename, ..., ext="bz2", FUN=bzfile)
 ## Default S3 method:
bunzip2(filename, ..., ext="bz2", FUN=bzfile)
 ## Default S3 method:
gzip(filename, ..., ext="gz", FUN=gzfile)
 ## Default S3 method:
gunzip(filename, ..., ext="gz", FUN=gzfile)

Arguments

filename	Pathname of input file.
destname	Pathname of output file.
temporary	If TRUE, the output file is created in a temporary directory.
skip	If TRUE and the output file already exists, the output file is returned as is.
overwrite	If TRUE and the output file already exists, the file is silently overwritten, otherwise an exception is thrown (unless skip is TRUE).
remove	If TRUE, the input file is removed afterward, otherwise not.
BFR.SIZE	The number of bytes read in each chunk.
...	Passed to the underlying function or alternatively not used.
method	A character string specifying how to infer whether a file is compressed or not.
ext, fileClass, FUN	(internal) Filename extension, file class, and a connection function used to read from/write to file.

Details

Internally bzfile() and gzfile() (see connections) are used to read (write) files. If the process is interrupted before completed, the partially written output file is automatically removed.

Value

Returns the pathname of the output file. The number of bytes processed is returned as an attribute.

isCompressedFile(), isGzipped() and isBzipped() return a logical. Note that with method = "extension" (default), only the filename extension is used to infer whether the file is compressed or not. Specifically, it does not matter whether the file actually exists or not.

Author(s)

Henrik Bengtsson

Examples

  ## bzip2
  cat(file="foo.txt", "Hello world!")
  print(isBzipped("foo.txt"))
  print(isBzipped("foo.txt.bz2"))

  bzip2("foo.txt")
  print(file.info("foo.txt.bz2"))
  print(isBzipped("foo.txt"))
  print(isBzipped("foo.txt.bz2"))

  bunzip2("foo.txt.bz2")
  print(file.info("foo.txt"))

  ## gzip
  cat(file="foo.txt", "Hello world!")
  print(isGzipped("foo.txt"))
  print(isGzipped("foo.txt.gz"))

  gzip("foo.txt")
  print(file.info("foo.txt.gz"))
  print(isGzipped("foo.txt"))
  print(isGzipped("foo.txt.gz"))

  gunzip("foo.txt.gz")
  print(file.info("foo.txt"))

  ## Cleanup
  file.remove("foo.txt")

R.utils documentation built on Nov. 18, 2023, 1:09 a.m.