[Rd] proposal: lattice/levelplot with zlim

[Wolfram Fischer - Z/I/M]

I suggest to add an argument zlim to levelplot().

This would be a help e.g. to plot a sort of correlogram
(or corrgram, how Micheal Friendly named it, c.f.:
http://euclid.psych.yorku.ca/SCS/Papers/corrgram.pdf)

When using panel.catlevelplot which I suggested yesterday
the graphic becomes even nicer.

Wolfram



#---- ADDITIONAL ARGUMENT FOR levelplot() --------------------------

    zlim = range(z[!is.na(z)]),


#---- ADDITIONAL CODE IN levelplot() -------------------------------

                #--- ORIGINAL ---
#   zrng <- extend.limits(range(z[!is.na(z)]))
                #--- NEW ---
    zrng <- extend.limits( zlim )


#---- EXAMPLE ------------------------------------------------------

library(EMV)
data(swiss)
example.corplot.swiss <- function( ... ){
    x.cor <- cor( knn( as.matrix( swiss ) )$data )
    diag( x.cor ) <- 0
    x.names <- colnames( swiss )
    x.cor.data  <- data.frame(
          x     = rep( x.names, length( x.names ) )
        , y     = rep( x.names, each=length( x.names ) )
        , val   = as.vector( x.cor )
        )
    print( levelplot( val ~ x + y, data = x.cor.data
## --- omit next argument if panel.catlevelplot is not yet defined ---
        , panel = panel.catlevelplot
        , scales= list(
              x = list( labels = x.names, rot=90, alternating=F
                  , at = 1 : length( x.names ) )
            , y = list( labels = x.names, alternating=F
                  , at = 1 : length( x.names ) )
            )
        , zlim  = c( -1, 1 )
        , ...
        ))
}

#---- --------------------------------------------------------------