gplot error in rasterVis

Thanks for the quick reply. Yes, this works for me now.

One more follow-up question -- I'm trying to plot a raster on top of a
static google map image. I can do this:

library(RgoogleMaps)
library(raster)
library(maps)
library(ggmap)

r <- raster(ncol=10, nrow=10)
values(r) <- 1:ncell(r)
extent(r)<-c(-113.5732, -112.4852, 43.04848, 43.81728)

#not ideal-> no legend, raster not transparent
bsbMap<-get_map(location = c(lon = -113.027724, lat = 43.402726), zoom
= 8, maptype = 'terrain')
m <- ggmap(bsbMap)+ inset_raster(r, xmin(r), xmax(r), ymin(r), ymax(r))

but is there a way to control plotting of the raster (e.g., to set the
transparency or color scheme) and add a legend? I was hoping to do
this with geom_raster rather than inset_raster, but it looks like
ggmap doesn't work with geom_raster. I have used geom_raster to make a
similar map with state/county boundaries:

#would like to create this sort of overlay on a static google map
rdf <- rasterToPoints(r)
rdf <- data.frame(rdf)
colnames(rdf)<-c("lon","lat","T")

states<-map_data("state", region=c("idaho", "montana", "utah", "wyoming"))
counties<-map_data("county", region=c("idaho"))

g <- ggplot( data=rdf) + geom_raster(aes(x=lon, y=lat, fill=T) )
g<-g + scale_fill_gradient(name="T (C)", low="blue", high="orange")
g<-g + theme_bw() + xlim(c(-115.5,-110.5)) + ylim(c(41.5,45))
g<-g + geom_path(data=states, aes(x=long,y=lat,group=group),
colour="black", alpha=0.5)
g<-g + geom_path(data=counties, aes(x=long,y=lat,group=group),
colour="black", alpha=0.5)

Any suggestions for the most efficient way to create this sort of
raster overlay on a google map?

Thanks,
Natalie

On Thu, May 30, 2013 at 6:52 AM, Oscar Perpi??n Lamigueiro
<oscar.perpinan at gmail.com> wrote:

Hi,

With the current definition of gplot you have to add the layers you need
to plot (that's why you get the error "No layers to plot"). Take a look
at the example of the help page. With your example:

gplot(r) + geom_tile(aes(fill=value)) + coord_equal()

On the other hand, the warning when you use gplot is because both
latticeExtra and ggplot2 define the function layer. If ggplot2 is loaded
after rasterVis, the layer definition from latticeExtra becomes
masked. If you plan to use latticeExtra (for example, to add layers over
the result of a levelplot call) you should load ggplot2 before
rasterVis.

Best,

Oscar.

Natalie Wagenbrenner <nwagenbrenner at gmail.com> writes:

I'm trying to use gplot() in rasterVis to plot a RasterLayer object
using ggplot2
graphics, but I keep getting an error.  Here is a reproducible
example:

library(raster)
library(rasterVis)

r <- raster(ncol=10, nrow=10)
values(r) <- 1:ncell(r)
gplot(r)

The following `from` values were not present in `x`: col, color, pch,
cex, lty, lwd, srt, adj, bg, fg, min, max
Error: No layers in plot

I see the following warning when I load rasterVis:

Loading required package: ggplot2

Attaching package: ?ggplot2?

The following object(s) are masked from ?package:latticeExtra?:

    layer

Perhaps this is part of the problem? Or I am misunderstanding the
gplot() methods somehow? Thanks for any suggestions.

Natalie

Session info:

R version 2.14.1 (2011-12-22)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_CA.UTF-8       LC_NUMERIC=C
LC_TIME=en_CA.UTF-8
 [4] LC_COLLATE=en_CA.UTF-8     LC_MONETARY=en_CA.UTF-8
LC_MESSAGES=en_CA.UTF-8
 [7] LC_PAPER=C                 LC_NAME=C
LC_ADDRESS=C
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_CA.UTF-8
LC_IDENTIFICATION=C

attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets
methods   base

other attached packages:
 [1] ggmap_2.3           RgoogleMaps_1.2.0.3 png_0.1-4
maps_2.3-2          rasterVis_0.20-07
 [6] hexbin_1.26.2       latticeExtra_0.6-24 RColorBrewer_1.0-5
lattice_0.20-0      ggplot2_0.9.3.1
[11] rgdal_0.8-9         raster_2.1-25       sp_1.0-9
ncdf_1.6.6          vimcom_0.9-8
[16] setwidth_1.0-3      colorout_1.0-0

loaded via a namespace (and not attached):
 [1] colorspace_1.2-2 dichromat_2.0-0  digest_0.6.3     gtable_0.1.2
  labeling_0.1     mapproj_1.2-1
 [7] MASS_7.3-16      munsell_0.4      plyr_1.8         proto_0.3-10
  reshape2_1.2.2   rjson_0.2.12
[13] scales_0.2.3     stringr_0.6.2    zoo_1.7-9

--
Oscar Perpi??n Lamigueiro
Grupo de Sistemas Fotovoltaicos (IES-UPM)
Dpto. Ingenier?a El?ctrica (EUITI-UPM)
URL: http://procomun.wordpress.com
Twitter: @oscarperpinan