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

[Weidong Gu]

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