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
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))