Position legend in first plot of facet

Question

I would like to put my plot legend inside the plot, inside the first plot of a facet.

Here is some example code:

df=data.frame(
 x=runif(10),
 y=runi         


        

Answer 1

Or, building on @Richie Cotton's answer, since opts is deprecated in ggplot2 now (still assuming your plot is defined as p)

p + theme(legend.position = c(0.9, 0.6)
          ,legend.background = element_rect(fill = "white", colour = NA))

Answer 2

Assuming your plot is saved as p

p + opts(
  legend.position = c(0.9, 0.6), # c(0,0) bottom left, c(1,1) top-right.
  legend.background = theme_rect(fill = "white", colour = NA)
)

If you want the legend background partially transparent, change the fill to, e.g., "#ffffffaa".