As far as I can tell, there's no built-in way to get
capture.output() to capture messages (stderr) instead of
stdout ... suggested, fairly trivial, patch below.
f <- function() {
message("abc")
cat("def\n")
}
x <- capture.output(f())
## prints 'abc'
x ## value: "def"
source("~/R/r-devel/src/library/utils/R/capture.output.R")
x <- capture.output(f()) ## unchanged
x <- capture.output(f(),type="message") ## prints 'def': value 'abc'
Of course, if someone was going to mess with this function more,
it might be nice to have an option to have *both* streams captured ...
Index: capture.output.R
===================================================================
--- capture.output.R (revision 63969)
+++ capture.output.R (working copy)
@@ -16,8 +16,10 @@
# A copy of the GNU General Public License is available at
# http://www.r-project.org/Licenses/
-capture.output <- function(..., file=NULL, append=FALSE)
+capture.output <- function(..., file=NULL, append=FALSE,
+ type = c("output", "message"))
{
+ type <- match.arg(type)
args <- substitute(list(...))[-1L]
rval <- NULL; closeit <- TRUE
@@ -31,9 +33,9 @@
} else
stop("'file' must be NULL, a character string or a connection")
- sink(file)
+ sink(file,type=type)
## for error recovery: all output will be lost if file=NULL
- on.exit({sink(); if(closeit) close(file)})
+ on.exit({sink(type=type); if(closeit) close(file)})
pf <- parent.frame()
evalVis <- function(expr)
@@ -50,7 +52,7 @@
}
## we need to close the text connection before returning 'rval'
on.exit()
- sink()
+ sink(type=type)
if(closeit) close(file)
if(is.null(rval)) invisible(NULL) else rval
}
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