r - How do I arrange a variable list of plots using grid.arrange?

Question

library(ggplot2)
df <- data.frame(x=1:10, y=rnorm(10))
p1 <- ggplot(df, aes(x,y)) + geom_point()
plist <- list(p1,p1,p1,p1,p1)
# In my real example,a plot function will fit a ggplot to a list of datasets 
#and return a list of ggplots like the example above.

I'd like to arrange the plots using grid.arrange() in gridExtra.

How would I do this if the number of plots in plist is variable?

This works: grid.arrange(plist[[1]],plist[[2]],plist[[3]],plist[[4]],plist[[5]])

but I need a more general solution. thoughts?

Answer 1

How about this:

library(gridExtra)
n <- length(plist)
nCol <- floor(sqrt(n))
do.call("grid.arrange", c(plist, ncol=nCol))