ggplot2 将图例移动到绘图区域，键周围没有边框

Question

Hi im trying to add my legend area to my plot area without the white borders around my key. So far i have this:

Legend in plot area but white border present:

Legend style i want:

ggplot(data=Pig, aes(x=breed, y= p1_plus_p3_fat_depth_mm, color=sex))+
geom_boxplot()+
theme(legend.title=element_blank()) +
theme(panel.grid.major = element_blank()) +
theme(panel.grid.minor = element_blank())+
xlab("Pig Breed") +
ylab("The P1 and P3 Fat Depth in mm")+
scale_colour_discrete(name  ="Sex",breaks=c("B", "S"),labels=c("Boar", "Sow"))+
theme(legend.justification = c(1, 1), legend.position = c(1, 1))+
theme(legend.background = element_rect(fill="transparent"))

Answer 1

You will need to use legend.key = element_blank() to drop the background and borders around the boxplot icons.

ggplot(data=iris[c("Species", "Sepal.Length")], aes(x=Species, y= Sepal.Length, color=Species))+
  geom_boxplot()+
  theme(legend.title=element_blank()) +
  theme(panel.grid.major = element_blank()) +
  theme(panel.grid.minor = element_blank())+
  theme(legend.justification = c(1, 1), legend.position = c(1, 1))+
  theme(legend.background = element_blank(),
        legend.key = element_blank())

I prefer using element_blank() which will remove a theme element as opposed to setting it to transparent and leaving it there. I've found depending on the graphics device the transparent can be interpreted differently.