ggplot2 make legend key fill transparent

Question

I am trying to make the legend key fill for a ggplot transparent. I followed the instructions on one of Hadley\'s ggplot2 guides for changing the legend key fill, but for some

Answer 1

I was going crazy with this behavior as well, so here is a working solution for your example:

plot + guides(color=guide_legend(override.aes=list(fill=NA)))

Check this thread for more information.