How we use ggplot2like if there is already a user defined par.settings function

Question

The example from the ggplot2like help returns ggplot2like() to par.settings, as follows:

library(lattice)
library(latticeExtra)

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

But how shall we use ggplot2like and axis = axis.grid if we have already a user-defined function for par.settings, as follows:

mysettings <- list(par.main.text = list(font = 1, cex = 1))

xyplot(exp(1:10) ~ 1:10, type = "b", main = "Title",
  par.settings = mysettings)

Answer 1

Function modifyList can be used to modify ggplot2like theme:

mysettings <- list(par.main.text = list(font = 1, cex = 1))

xyplot(exp(1:10) ~ 1:10, type = "b", main = "Title",
  par.settings = modifyList(ggplot2like(), mysettings), axis = axis.grid)

Works because a lattice theme is list of parameters. Function modifyList use second list to modify (add or replace) elements in first list.

As an alternative you could setup your settings at first:

mysettings <- modifyList(
    ggplot2like()
    ,list(par.main.text = list(font = 1, cex = 1))
)

xyplot(exp(1:10) ~ 1:10, type = "b", main = "Title",
  par.settings = mysettings, axis = axis.grid)