[R-sig-Geo] how to pass panel index in spplot

[Edzer Pebesma]

Dear Weidong,

for multi-group panel functions, the way to retrieve subscripts in
custom panel functions is

panel = function(x,y,subscripts, ...) {
 ... # do sth with subscripts here
}

see also

library(lattice)
?panel.superpose

I hope this helped,

Weidong Gu wrote:
> Hi,
> 
> I have a question about spplot: can it transfer somehow panel index, such as subscripts in xyplot to panels. 
> 
> The question arose when I needed to plot numbers of disease incidents on state map. The reproducible code is below. I thought panel=function () might be the solution but I couldn't get panel index in individual panels.
> 
> library(maps)
> library(maptools)
> state=map('state',plot=F,fill=T)
> IDs=sapply(strsplit(state$names,':'), function(x) x[1])
> crs=CRS('+proj=longlat +ellps=WGS84')
> sp.st=map2SpatialPolygons(state, IDs, proj4string=crs)
> 
> state.inc=data.frame(State=sapply(slot(sp.st,'polygons'),function(x) slot(x,'ID')))
> state.inc$D1=rpois(length(state.inc$State),100)
> state.inc$D2=rpois(length(state.inc$State),150)
> row.names(state.inc)=state.inc$State
> inc.spdf=SpatialPolygonsDataFrame(sp.st,state.inc)
> 
> spplot(inc.spdf, zcol=2:3,
>     panel = function(...) {
>         sp.polygons(inc.spdf) 
>         sp.text(coordinates(inc.spdf),zcol)
>     }
>     )
> 
> I would appreciate you help and advice.
> 
> Weidong Gu
> University of Alabama, Birmingham
> 220A Bevill Biomedical Research Bldg
> 845 19th Street S., Birmingham, Alabama 35294
> 
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> R-sig-Geo at stat.math.ethz.ch
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de