Hi David,
Putting a print statement around your spplot command solves your
problem. This behaviour is common for trellis graphics plot methods
(such as spplot). This is the command including print:
print(spplot(meuse, c("ffreq"),
sp.layout=list(l2,l3,l4,l5),col.regions="black",pch=c(1,2,3),
key.space=list(x=0.1,y=.95,corner=c(0,1))))
These kinds of questions maybe are not specific to sp, but still might
generate more response from the r-sig-geo mailing list.
cheers,
Paul
David wrote:
I want to use spplot inside a loop to itteratively produce png files.
for (i in 1:5){
png(file=paste("myPlot",i,".png",sep=""),bg="white",height=500,width=500)
library(lattice)
trellis.par.set(sp.theme()) # sets bpy.colors() ramp
data(meuse)
coordinates(meuse) <- ~x+y
l2 = list("SpatialPolygonsRescale", layout.north.arrow(), offset =
c(181300,329800), scale = 400)
l3 = list("SpatialPolygonsRescale", layout.scale.bar(), offset =
c(180500,329800),
scale = 500, fill=c("transparent","black"))
l4 = list("sp.text", c(180500,329900), "0")
l5 = list("sp.text", c(181000,329900), "500 m")
spplot(meuse, c("ffreq"),
sp.layout=list(l2,l3,l4,l5),col.regions="black",pch=c(1,2,3),
key.space=list(x=0.1,y=.95,corner=c(0,1)))
dev.off()
}
The above example fails to write the output to the file. When the loop
is finished the file size of each file is 0Kb. If I perform the work
of the loop manually, ie. setting "i <- 1", "i <- 2" etc before
manually running the loop contents then there is no problem. There is
also no problem if I replace all the spplot stuff with say
"hist(rnorm(100))".
The same behaviour is reproduced with levelplot too so is not sp specific.
for (i in 1:5){
png(file=paste("sillyPlot",i,".png",sep=""),bg="white",height=500,width=500)
x <- seq(pi/4, 5 * pi, length = 100)
y <- seq(pi/4, 5 * pi, length = 100)
r <- as.vector(sqrt(outer(x^2, y^2, "+")))
grid <- expand.grid(x=x, y=y)
grid$z <- cos(r^2) * exp(-r/(pi^3))
levelplot(z~x*y, grid, cuts = 50, scales=list(log="e"), xlab="",
ylab="", main="Weird Function", sub="with log scales",
colorkey = FALSE, region = TRUE)
dev.off()
}
How should I correctly write these loops to do as intended?
cheers
David
--
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
Heidelberglaan 2
P.O. Box 80.115
3508 TC Utrecht
Phone: +31302535773
Fax: +31302531145
http://intamap.geo.uu.nl/~paul
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