Thanks, it works nicely. In the meantime, I came across a similar
approach taken in the documentation of ggplot2, using a small sample
of the diamonds data.
Thanks all again,
baptiste
On 21 Oct 2007, at 12:25, Katharine Mullen wrote:
I'm not aware of any existing function that does what you want, but
you
could easily write a function to sample from x, y, z, and then pass
the
sampled values to image. e.g.,
sam - function(sx,sy,x,y,z){
xind-seq(1,length(x),by=sx)
yind-seq(1,length(y),by=sy)
samplex-x[xind]
sampley-y[yind]
samplez-z[xind,yind]
list(x=samplex,y=sampley,z=samplez)
}
newval-sam(sx=13.3,sy=15,x=x,y=y,z=z)
image(newval$x,newval$y,newval$z)
On Sun, 21 Oct 2007, [ISO-8859-1] baptiste Auguié wrote:
Dear R gurus,
I'm trying to visualize a matrix 256 x 920 using image(), but i find
the display too slow (~ 1 minute –– admittedly, my iBook G4 isn't
very fast). The aim is not to get a good resolution image, but rather
have a quick look at the matrix. I couldn't find a way to plot a
smaller set of points from my data in a sensible manner (basically, i
want to decrease the resolution). Is there an easy option for this
purpose in image(), or possibly the lattice equivalent?
Minimal example:
x-c(1:256)
y-c(1:920)
z-x%*%t(y)
image(x,y,z)
Best regards,
baptiste
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