save {base}

R Documentation

Save R Objects

Description

save writes an external representation of R objects to the specified file. The objects can be read back from the file at a later date by using the function load (or data in some cases).

save.image() is just a short-cut for ‘save my current workspace’, i.e., save(list = ls(all=TRUE), file = ".RData"). It is also what happens with q("yes").

Usage

save(..., list = character(0L),
     file = stop("'file' must be specified"),
     ascii = FALSE, version = NULL, envir = parent.frame(),
     compress = !ascii, eval.promises = TRUE, precheck = TRUE)

save.image(file = ".RData", version = NULL, ascii = FALSE,
           compress = !ascii, safe = TRUE)

Arguments

...	the names of the objects to be saved (as symbols or character strings).
list	A character vector containing the names of objects to be saved.
file	a connection or the name of the file where the data will be saved. Must be a file name for workspace format version 1.
ascii	if TRUE, an ASCII representation of the data is written. The default value of ascii is FALSE which leads to a more compact binary file being written.
version	the workspace format version to use. NULL specifies the current default format. The version used from R 0.99.0 to R 1.3.1 was version 1. The default format as from R 1.4.0 is version 2.
envir	environment to search for objects to be saved.
compress	logical specifying whether saving to a named file is to use compression. Ignored when file is a connection and for workspace format version 1.
eval.promises	logical: should objects which are promises be forced before saving?
precheck	logical: should the existence of the objects be checked before starting to save (and in particular before opening the file/connection)? Does not apply to version 1 saves.
safe	logical. If TRUE, a temporary file is used for creating the saved workspace. The temporary file is renamed to file if the save succeeds. This preserves an existing workspace file if the save fails, but at the cost of using extra disk space during the save.

Details

The names of the objects specified either as symbols (or character strings) in ... or as a character vector in list are used to look up the objects from environment envir. By default promises are evaluated, but if eval.promises = FALSE promises are saved (together with their evaluation environments). (Promises embedded in objects are always saved unevaluated.)

All R platforms use the XDR (bigendian) representation of C ints and doubles in binary save-d files, and these are portable across all R platforms. (ASCII saves used to be useful for moving data between platforms but are now mainly of historical interest.)

Default values for the ascii, compress, safe and version arguments can be modified with the save.defaults option (used both by save and save.image), see also the example section below. If a save.image.defaults option is set it overrides save.defaults for function save.image (which allows this to have different defaults).

It is possible to compress later (with gzip) a file saved with compress = FALSE: the effect is the same as saving with compress = TRUE.

Warnings

The ... arguments only give the names of the objects to be saved: they are searched for in the environment given by the envir argument, and the actual objects given as arguments need not be those found.

Saved R objects are binary files, even those saved with ascii = TRUE, so ensure that they are transferred without conversion of end of line markers and of 8-bit characters. The lines are delimited by LF on all platforms.

Although the default version has not changed since R 1.4.0, this does not mean that saved files are necessarily backwards compatible. You will be able to load a saved image into an earlier version of R unless use is made of later additions (for example, raw vectors or external pointers).

Note

The most common reason for failure is lack of write permission in the current directory. For save.image and for saving at the end of a session this will shown by messages like

    Error in gzfile(file, "wb") : unable to open connection
    In addition: Warning message:
    In gzfile(file, "wb") :
      cannot open compressed file '.RDataTmp',
      probable reason 'Permission denied'

The defaults were changed to use compressed saves for save in 2.3.0 and for save.image in 2.4.0. Any recent version of R can read compressed save files, and a compressed file can be uncompressed (by gzip -d) for use with very old versions of R.

See Also

dput, dump, load, data.

Examples

x <- stats::runif(20)
y <- list(a = 1, b = TRUE, c = "oops")
save(x, y, file = "xy.Rdata")
save.image()
unlink("xy.Rdata")
unlink(".RData")

# set save defaults using option:
options(save.defaults=list(ascii=TRUE, safe=FALSE))
save.image()
unlink(".RData")

---