ggplot2: how to remove slash from geom_density legend

Question

I'm trying to plot some overlapping density plots in ggplot2. I'm running into a problem where I cannot remove the diagonal slash from the legend. I have tried using scale_fill_manual() and legend.key as well as the hack from R Cookbook, but I cant seem to get it right.

data(iris) iris=iris cols=brewer.pal(3,"Set1")  ggplot(iris) +      geom_density(position="identity",aes(x=iris$Sepal.Length,fill=cols[1]),         colour="black",alpha=.5) +     geom_density(position="identity",aes(x=iris$Sepal.Width,fill=cols[2]),         colour="black",alpha=.5)+       theme_bw() +     scale_fill_identity(guide="legend",labels=c("Sepal Width","Sepal Length"))+     xlab("X axis") +     theme(panel.background=element_blank(),         legend.title=element_blank(),         legend.key = element_rect(),         legend.background = element_blank(),         legend.justification=c(1,0),          legend.position=c(.75,.5),         panel.grid.major = element_blank(),         panel.grid.minor = element_blank(),         panel.border = element_blank(),         panel.background = element_blank()) 

What can I do to solve this?

Answer 1

Try this:

+ guides(fill = guide_legend(override.aes = list(colour = NULL))) 

although that removes the black outline as well...which can be added back in by change the theme to:

legend.key = element_rect(colour = "black") 

I completely forgot to add this important note: do not specify aesthetics via x=iris$Sepal.Length using the $ operator! That is not the intended way to use aes() and it will lead to errors and unexpected problems down the road.