[R] lattice contourplot line types

[Sundar Dorai-Raj]

The only way I can figure out to do this is to use two calls to
panel.contourplot:

library(lattice)
x <- seq(-2, 2, length = 20)
y <- seq(-2, 2, length = 20)
grid <- expand.grid(x=x, y=y)
grid$z <- dnorm(grid$x) * dnorm(grid$y)
contourplot(z ~ x * y, grid,
            panel = function(at, lty, col, ...) {
              at.o <- at[seq(1, length(at), 2)]
              at.e <- at[seq(2, length(at), 2)]
              panel.contourplot(at = at.o, lty = 1, col = "blue", ...)
              panel.contourplot(at = at.e, lty = 4, col = "red", ...)
            },
            at = pretty(grid$z, 10))

HTH,

--sundar

On Sun, Feb 22, 2009 at 12:45 PM, Andrew Beckerman
<a.beckerman at sheffield.ac.uk> wrote:
> Dear all -
>
> I would like to adjust the line type of specific contours in contourplot
> from the lattice package, but it seems like lty does not take a list in the
> call.
>
> Here is my call to contourplot:
>
> contourplot(preds~size+trt|Size.Name,
>        data=pred.dat,layout=c(2,4),
>        at=c(0.025,0.5,0.975),
>        par.strip.text=list(cex=1.2),
>        scales=list(cex=0.5),
>        xlab=list("Size",cex=1.2),
>        ylab=list("Treatment",cex=1.2),
>        panel=function(x,y,z,...){
>                panel.contourplot(x,y,z,lwd=1,...)
>                panel.grid(h=-1,v=-1,col="grey",...)})
>
> I would like to specify lty=c(2,1,2) corresponding to the
> at=c(0.025,0.5,0.975), and have tried this in both the core part of the
> call, and in panel.countourplot.  However, it only recognises the first
> type.
>
> If there is no straightforward answer, I can provide the data.
>
> Best wishes,
> Andrew
>
> R version 2.8.1 (2008-12-22)
> i386-apple-darwin8.11.1
>
> locale:
> en_GB.UTF-8/en_GB.UTF-8/C/C/en_GB.UTF-8/en_GB.UTF-8
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] MASS_7.2-45     lattice_0.17-17
>
> loaded via a namespace (and not attached):
> [1] grid_2.8.1
>
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