R help - Aug 2010 - Does R always insist on sending plot output to a file?

I need to write the output of a R plot to a Java OutputStream. It looks like
R insists on sending it's output to a file. Is there anyway to get bytes
directly from the output of a plot so I can write it with Java? Writing it
to a file is too slow.

Is there a parameter in the graphics device function png(..) that directs
output to a variable in memory? 

x <- plot(.)  would make sense.
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Take a look on help page for ?recordPlot

On Wed, Aug 18, 2010 at 10:49 PM, Donald Paul Winston <
satchwinston@yahoo.com> wrote:
>
> I need to write the output of a R plot to a Java OutputStream. It looks
> like
> R insists on sending it's output to a file. Is there anyway to get
bytes
> directly from the output of a plot so I can write it with Java? Writing it
> to a file is too slow.
>
> Is there a parameter in the graphics device function png(..) that directs
> output to a variable in memory?
>
> x <- plot(.)  would make sense.
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/Does-R-always-insist-on-sending-plot-output-to-a-file-tp2330557p2330557.html
> Sent from the R help mailing list archive at Nabble.com.
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

Donald,

At least for the PDF device (I know you asked about png, but I believe
they are similar), the answer no. Ultimately, this device calls the
standard C function fopen, and writes its data to the resulting file
stream.

If you're using GNU Linux, you might trick R into writing to a fifo (a
named pipe, see 'man fifo'), or some other in-memory device, and read
from it with another program. My initial experiments with this, however,
were not successful.

A better solution here, would be to have the various graphics devices
write to an R connection, as do most other R functions that input and
output data. In this way, we could write graphics data to a RAW
connection (rawConnection()), which is essentially a memory buffer. 

There are two obvious barriers to this:
1. C level I/O routines (e.g. fprintf) are heavily integrated into the
graphics device code. Hence, accommodating R connections would require
significant changes.
2. The graphics devices are mostly implemented in C, and there is (at
present) no interface to R connections at the C level.

-Matt

On Wed, 2010-08-18 at 21:49 -0400, Donald Paul Winston
wrote:
> I need to write the output of a R plot to a Java OutputStream. It looks
like
> R insists on sending it's output to a file. Is there anyway to get
bytes
> directly from the output of a plot so I can write it with Java? Writing it
> to a file is too slow.
> 
> Is there a parameter in the graphics device function png(..) that directs
> output to a variable in memory? 
> 
> x <- plot(.)  would make sense.
-- 
Matthew S. Shotwell
Graduate Student 
Division of Biostatistics and Epidemiology
Medical University of South Carolina