R: Read R Code from a File or a Connection

source {base}

R Documentation

Read R Code from a File or a Connection

Description

source causes R to accept its input from the named file or URL (the name must be quoted) or connection. Input is read and parsed by from that file until the end of the file is reached, then the parsed expressions are evaluated sequentially in the chosen environment.

Usage

source(file, local = FALSE, echo = verbose, print.eval = echo,
       verbose = getOption("verbose"),
       prompt.echo = getOption("prompt"),
       max.deparse.length = 150, chdir = FALSE,
       encoding = getOption("encoding"))

Arguments

`file`	a connection or a character string giving the pathname of the file or URL to read from.
`local`	if `local` is `FALSE`, the statements scanned are evaluated in the user's workspace (the global environment), otherwise in the environment calling `source`.
`echo`	logical; if `TRUE`, each expression is printed after parsing, before evaluation.
`print.eval`	logical; if `TRUE`, the result of `eval(i)` is printed for each expression `i`; defaults to `echo`.
`verbose`	if `TRUE`, more diagnostics (than just `echo = TRUE`) are printed during parsing and evaluation of input, including extra info for each expression.
`prompt.echo`	character; gives the prompt to be used if `echo = TRUE`.
`max.deparse.length`	integer; is used only if `echo` is `TRUE` and gives the maximal length of the “echo” of a single expression.
`chdir`	logical; if `TRUE` and `file` is a pathname, the R working directory is temporarily changed to the directory containing `file` for evaluating.
`encoding`	character string. The encoding to be assumed when `file` is a character string: see `file`. A possible value is `"unknown"`: see the Details.

Details

All versions of R accept input from a connection with end of line marked by LF (as used on Unix), CRLF (as used on DOS/Windows) or CR (as used on classic MacOS). The final line can be incomplete, that is missing the final EOL marker.

If options("keep.source") is true (the default), the source of functions is kept so they can be listed exactly as input. This imposes a limit of 128K chars on the function size and a nesting limit of 265. Use option(keep.source = FALSE) when these limits might take effect: if exceeded they generate an error.

This paragraph applies if file is a filename (rather than a connection). If encoding = "unknown", an attempt is made to guess the encoding. The result of localeToCharset() is used a guide. If encoding has two or more elements, they are tried in turn until the file/URL can be read without error in the trial encoding.

References