[R] Overlaying two plots

[dxc13]

Hi useR's,

I want to overlay an image plot over a world map and I can do it, but just
not the way I need to do it.  Here is the code I am using (with data file
attached) to create my baseline map:
library(sp)
load("TM_WORLD_BORDERS_SIMPL-0.2.RData")
par(bty="l")
plot(wrld_simpl, axes = TRUE, ylim = c(-90, 90), xlim=c(-180, 180), asp=1.5)
lim <- par("usr")
abline(v=-180, h=90, col="red")  #Image plot needs to be inside this square#
abline(v=180, h=-90, col="red")

The last two statements create a square on the map between the latitude and
longitude limits of the world.  I want to place the following image plot
(data matrix attached) inside that square region and then overlay the world
map again.  When I use the following code, the image plot takes up the whole
plot screen and is not within the square region and thus when I overlay the
world map, the coordinates will be off.

df <- as.matrix(read.table("kz_time1.txt", header=F))
dff <- apply(df, 2, rev)
image(t(dff), xlab="", ylab="", axes=FALSE)

par(new=TRUE)
plot(wrld_simpl, axes = TRUE, ylim = c(-90, 90), xlim=c(-180, 180), asp =
1.5, xlab="Longitude", ylab="Latitude")
abline(v=-180, h=90, col="red") 
abline(v=180, h=-90, col="red")

Can anyone help?
Thanks in advance.
dxc13

  http://www.nabble.com/file/p23526662/TM_WORLD_BORDERS_SIMPL-0.2.RData
TM_WORLD_BORDERS_SIMPL-0.2.RData 
http://www.nabble.com/file/p23526662/kz_time1.txt kz_time1.txt 
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