Plotting shapefiles on top of Google map tiles

Dear prof. Robert Hijmans,

I tryed your suggestion (under Vista), but got the following errors:

gmap(a)

Loading required package: RgoogleMaps
Error in paste(googleurl, "center=", center, "&zoom=", zoom, "&size=",? :
? object 'localhostkey' not found

sessionInfo()

R version 2.9.0 alpha (2009-03-26 r48224)
i386-pc-mingw32
locale:
LC_COLLATE=English_Canada.1252;LC_CTYPE=English_Canada.1252;LC_MONETARY=English_Canada.1252;LC_NUMERIC=C;LC_TIME=English_Canada.1252
attached base packages:
[1] stats???? graphics? grDevices utils???? datasets? methods?? base
other attached packages:
[1] maptools_0.7-20?? foreign_0.8-34??? sp_0.9-32???????? RgoogleMaps_1.1.6
fortunes_1.3-6
loaded via a namespace (and not attached):
[1] grid_2.9.0????? lattice_0.17-20 tools_2.9.0

Any idea?

bests

milton


On Mon, Jan 18, 2010 at 2:06 AM, Robert J. Hijmans <r.hijmans at gmail.com>
wrote:

Patrick,

I have had some success with plotting sp objects on top of G maps with
this function


gmap <- function(xy, maptype='terrain', ...) {
? ?require(RgoogleMaps)
? ? ? ?fun = points
? ? ? ?if (inherits(xy, 'Spatial')) {
? ? ? ? ? ? ? ?b = bbox(xy)
? ? ? ? ? ? ? ?if (inherits(xy, 'SpatialPoints')) {
? ? ? ? ? ? ? ? ? ? ? ?xy = coordinates(xy)
? ? ? ? ? ? ? ?} else {
? ? ? ? ? ? ? ? ? ? ? ?x = unlist(lapply(xy at polygons, function(i)slot(i,
'Polygons')))
? ? ? ? ? ? ? ? ? ? ? ?x = lapply(x, function(x)slot(x, 'coords'))
? ? ? ? ? ? ? ? ? ? ? ?xy = matrix(ncol=2, nr=0)
? ? ? ? ? ? ? ? ? ? ? ?for (i in 1:length(x)) xy = rbind(xy, x[[i]],
c(NA,NA))
? ? ? ? ? ? ? ? ? ? ? ?fun = lines
? ? ? ? ? ? ? ?}
? ? ? ?} else {
? ? ? ? ? ? ? ?b = rbind(range(xy[,1], na.rm=TRUE), range(xy[,2],
na.rm=TRUE))
? ? ? ?}
? ? ? ?mykey <- ?### fill in your google maps API key for
http://localhost/
? ?gm <- GetMap.bbox(key=localhostkey, lonR=b[1,], latR=b[2,],
maptype=maptype)
? ?tmp <- PlotOnStaticMap(gm, lon=xy[,1], lat=xy[,2], FUN=fun, verbose=0,
... )
}


a = matrix(runif(100)*100-50, ncol=2)
gmap(a)

library(sp)
gmap(SpatialPoints(a), col='red', cex=2, pch='+')

library(maptools)
data(wrld_simpl)
hti = wrld_simpl[wrld_simpl$ISO3=='HTI',]
gmap(hti, lwd=2, col='red')


Hth,
Robert


On Sat, Jan 16, 2010 at 5:35 PM, Patrick Crutcher <pcrutcher at gmail.com>
wrote:

I have some shapefiles I want to plot over Google Maps tiles. I have
polygons, lines and point data. What's the most efficient way to do
this?
One path might be to use the pkg RgoogleMaps, however, it is still
unclear
to me how to do this. I assume using PlotonStaticMap with some
combination
of reformatting the shapefile data. Thanks.

P.

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