| sink {base} | R Documentation |
Send R Output to a File
Description
sink diverts R output to a connection (and stops such diversions).
sink.number() reports how many diversions are in use.
sink.number(type = "message") reports the number of the
connection currently being used for error messages.
Usage
sink(file = NULL, append = FALSE, type = c("output", "message"),
split = FALSE)
sink.number(type = c("output", "message"))
Arguments
file |
a writable connection or a character string naming the
file to write to, or |
append |
logical. If |
type |
character string. Either the output stream or the messages stream. The name will be partially matched so can be abbreviated. |
split |
logical: if |
Details
sink diverts R output to a connection (and must be used again
to finish such a diversion, see below!). If file is a
character string, a file connection with that name will be established
for the duration of the diversion.
Normal R output (to connection stdout) is diverted by
the default type = "output". Only prompts and (most)
messages continue to appear on the console. Messages sent to
stderr() (including those from message,
warning and stop) can be diverted by
sink(type = "message") (see below).
sink() or sink(file = NULL) ends the last diversion (of
the specified type). There is a stack of diversions for normal
output, so output reverts to the previous diversion (if there was
one). The stack is of up to 21 connections (20 diversions).
If file is a connection it will be opened if necessary (in
"wt" mode) and closed once it is removed from the stack of
diversions.
split = TRUE only splits R output (via Rvprintf) and
the default output from writeLines: it does not split
all output that might be sent to stdout().
Sink-ing the messages stream should be done only with great care.
For that stream file must be an already open connection, and
there is no stack of connections.
If file is a character string, the file will be opened using
the current encoding. If you want a different encoding (e.g., to
represent strings which have been stored in UTF-8), use a
file connection — but some ways to produce R output
will already have converted such strings to the current encoding.
Value
sink returns NULL.
For sink.number() the number (0, 1, 2, ...) of diversions of
output in place.
For sink.number("message") the connection number used for
messages, 2 if no diversion has been used.
Warning
Do not use a connection that is open for sink for any other
purpose. The software will stop you closing one such inadvertently.
Do not sink the messages stream unless you understand the source code implementing it and hence the pitfalls.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer.
See Also
Examples
sink("sink-examp.txt")
i <- 1:10
outer(i, i)
sink()
## capture all the output to a file.
zz <- file("all.Rout", open = "wt")
sink(zz)
sink(zz, type = "message")
try(log("a"))
## revert output back to the console -- only then access the file!
sink(type = "message")
sink()
file.show("all.Rout", delete.file = TRUE)