dput: Write an Object to a File or Recreate it

Description

Writes an ASCII text representation of an R object to a file or connection, or uses one to recreate the object.

Usage

dput(x, file = "", control = c("keepNA", "keepInteger", "showAttributes"))
dget(file, keep.source = FALSE)

Arguments

an object.

file

either a character string naming a file or a connection. "" indicates output to the console.

control

character vector indicating deparsing options. See .deparseOpts for their description.

keep.source

logical: should the source formatting be retained when parsing functions, if possible?

Value

For dput, the first argument invisibly.For dget, the object created.

Details

dput opens file and deparses the object x into that file. The object name is not written (unlike dump). If x is a function the associated environment is stripped. Hence scoping information can be lost.

Deparsing an object is difficult, and not always possible. With the default control, dput() attempts to deparse in a way that is readable, but for more complex or unusual objects (see dump, not likely to be parsed as identical to the original. Use control = "all" for the most complete deparsing; use control = NULL for the simplest deparsing, not even including attributes.

dput will warn if fewer characters were written to a file than expected, which may indicate a full or corrupt file system.

To display saved source rather than deparsing the internal representation include "useSource" in control. R currently saves source only for function definitions. If you do not care about source representation (e.g., for a data object), for speed set options(keep.source = FALSE) when calling source.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

Examples

Run this code

## Write an ASCII version of function mean to the file "foo"
dput(mean, "foo")
## And read it back into 'bar'
bar <- dget("foo")
## Create a function with comments
baz <- function(x) {
  # Subtract from one
  1-x
}
## and display it
dput(baz)
## and now display the saved source
dput(baz, control = "useSource")

## Numeric values:
xx <- pi^(1:3)
dput(xx)
dput(xx, control = "digits17")
dput(xx, control = "hexNumeric")
dput(xx, "foo"); dget("foo") - xx # slight rounding on all platforms
dput(xx, "foo", control = "digits17")
dget("foo") - xx # slight rounding on some platforms
dput(xx, "foo", control = "hexNumeric"); dget("foo") - xx
unlink("foo")

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