[R] plotting to stdout

[Duncan Murdoch]

On 9/7/2007 12:36 PM, Gene Selkov wrote:
> I have found two prior instances of this question in R-help, but I can't 
> find the answer, and I'm giving up on mindless tinkering.
> 
>    http://tolstoy.newcastle.edu.au/R/help/03a/5994.html
>    https://stat.ethz.ch/pipermail/r-help/2004-December/062259.html
> 
> I must be able to pipe the poltting commands to stdin and receive the plot 
> on stdout, with errors written to stderr, should any occur.
> 
> Here's what I tried:
> 
> file test.r:
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> postscript(stdout())
> plot(0)
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> This command:
> 
>     cat test.r | r --vanilla --slave
> 
> writes the output to a file named "1"
> 
> I have also tried:
> 
>    postscript(file=stdout())
>    postscript(file=file("stdout"))
> 
> In the latter case, the output goes to the file named "3".
> 
> Other graphics devices do the same thing.
> 
> It is interesting that write.table() supports the file=stdout() idiom. If 
> there is no official option to do this, I will appreciate a hint 
> about the spot in the code where I can fix it.

The ?postscript man page suggests that

postscript(file="", command="cat")

should do what you want (or maybe something other than "cat" for the 
passthrough).  The file arg is described as a character string, not a 
connection, so I wouldn't expect stdout() to work.  For write.table(), 
the arg is defined to be either the name of a file or an open connection.

Duncan Murdoch

> 
> Thanks,
> 
> --Gene
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> sessionInfo()
> R version 2.5.1 (2007-06-27)
> i386-apple-darwin8.10.1
> 
> locale:
> C
> 
> attached base packages:
> [1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  "methods"
> [7] "base"
> 
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