Hi
There are a couple of problems:
1.
Your 'outline' is much bigger than it needs to be. For example, the
following produces just Australia ...
outline <- map("worldHires", regions="Australia", exact=TRUE,
plot=FALSE) # returns a list of x/y coords
2.
The outline you get still has NA values in it (the coastline of
Australia in this database is a series of distinct lines; I don't know
why that is). Fortunately, you can stitch Australia back together again
like this ...
subset <- !is.na(outline$x)
polypath(c(outline$x[subset], NA, c(xbox, rev(xbox))),
c(outline$y[subset], NA, rep(ybox, each=2)),
col="light blue", rule="evenodd")
With those two changes, I get a much better result. You may want to
fiddle a bit more to add Tasmania and bits of PNG and Indonesia back in
the picture OR you could replace these problems with a different
approach and use a more sophisticated map outline via a "shapefile" (see
the 'sp' package and the 'maptools' package and possibly the R-sig-geo
mailing list).
Hope that helps.
Paul
On 07/16/13 23:17, Louise Wilson wrote:
library(mapdata)
image(x=110:155, y =-40:-10, z = outer(1:45, 1:30, "+"),
xlab = "lon", ylab = "lat")
outline <- map("worldHires", plot=FALSE) # returns a list of x/y coords
xrange <- range(outline$x, na.rm=TRUE) # get bounding box
yrange <- range(outline$y, na.rm=TRUE)
xbox <- xrange + c(-2, 2)
ybox <- yrange + c(-2, 2)
# create the grid path in the current device
polypath(c(outline$x, NA, c(xbox, rev(xbox))),
c(outline$y, NA, rep(ybox, each=2)),
col="light blue", rule="evenodd")
--
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
p...@stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/
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