R help - Sep 2003 - (no subject)

Dear all,

for an interactive web application i need to produce a lot of graphics (up
to 50) on demand.
In the moment i'm using the png format.

The png()
...using png(file="Rplot%03d.png", ...); 'plots' ;
dev.off()...
produces very good graphics. The problem is it takes too long to produce the
png files.
The bitmap()
...using bitmap(file="Rplot%03d.png", type="type =
"png256",...); 'plots';
dev.off()...
works really fast. But on my system the quality is poor compared with png()
even with a higher resolution than 72.

I'm using R 1.7.0 on Windows NT ; Ghostscript 8.00

1) Is there a possibility to speed up the png() 
    or to improve the quality of the png produced by bitmap()

2) How is it possible to give "names" to the png files (if producing
more
than one plot) instead of Name+serial number like Rplot%03d.png 

Any help would be appreciated

Johannes 

schnitzlerj at gmx.de

*PLEASE* always use a subject line!

On Sun, 14 Sep 2003, Johannes Schnitzler wrote:
> for an interactive web application i need to produce a lot of graphics (up
> to 50) on demand.
> In the moment i'm using the png format.
> 
> The png()
> ...using png(file="Rplot%03d.png", ...); 'plots' ;
dev.off()...
> produces very good graphics. The problem is it takes too long to produce
the
> png files.
> The bitmap()
> ...using bitmap(file="Rplot%03d.png", type="type =
"png256",...); 'plots';
> dev.off()...
> works really fast. But on my system the quality is poor compared with png()
> even with a higher resolution than 72.
> 
> I'm using R 1.7.0 on Windows NT ; Ghostscript 8.00
> 
> 1) Is there a possibility to speed up the png() 
>     or to improve the quality of the png produced by bitmap()
There is a possibility.  You have the source code, and we would be happy 
for you to optimize it and submit a faster version.  It looks up pixel 
values one at a time, and the use of block operations should speed it up.

> 2) How is it possible to give "names" to the png files (if
producing more
> than one plot) instead of Name+serial number like Rplot%03d.png 
Just start a new device for each plot!

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595