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 (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 for the 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.

References