How to set default par.settings theme in lattice

Question

For example:

mytheme <- trellis.par.get()
mytheme$strip.border$col = 'grey80'
mytheme$strip.background$col = 'grey80'
mytheme$axis.line$col = 'grey80'
mytheme$axis.text$col = 'grey60'
mytheme$plot.symbol$pch = 20
mytheme$plot.symbol$cex = .5
mytheme$plot.symbol$col = '#7AC5CD'
mytheme$plot.symbol$alpha = .8

l.sc <- update(scatter.lattice, par.settings = mytheme,
               layout = c(3, 2),
               between = list(x = 0.3, y = 0.3))
print(l.sc)

How can I set the default of par.settings to be mytheme ?

---

In the book Lattice Multivariate Data Visualization with R , page 131, the author gives this example:

lattice.options(lattice.theme = standard.theme("pdf"))

But I don't see how to adapt it to the current case. I tried:

lattice.options(lattice.theme = mytheme)

and it doesn't work.

Answer 1

The theme can be set persistently (ie, they will affect all subsequent plots until a new setting is specified) using the trellis.par.set() function:

 trellis.par.set(mytheme) ## mythme is a named list with settings parameters

where mytheme is a list( no need to call trellis.par.get()):

mytheme <- list()
mytheme$strip.border$col = 'grey80'
mytheme$strip.background$col = 'grey80'
mytheme$axis.line$col = 'grey80'
mytheme$axis.text$col = 'grey60'
mytheme$plot.symbol$pch = 20
mytheme$plot.symbol$cex = .5
mytheme$plot.symbol$col = '#7AC5CD'
mytheme$plot.symbol$alpha = .8

To set the theme temporarily , you set the "par.settings" argument of the lattice plotting function. For example this is how latticeExtra set the ggplot2 like theme:

library(latticeExtra) 
xyplot(exp(1:10) ~ 1:10, type = "b", 
       par.settings = ggplot2like())