ggplot2: how to separate geom_polygon and geom_line in legend keys?

Question

I want to:

• remove the line inside geom_polygon legend key and
• remove the border around the geom_line legend key.

The desired outpu

Answer 1

Do they have to be part of the same legend? If not, then you could use the 'fill' aesthetic for the polygon and the 'colour' aesthetic for the line:

ggplot(dat, aes(x = x, y = y)) +
    geom_polygon(aes(fill = "Border", group = id), colour="black") +
    geom_line(data = line, aes(colour = "Line"), size = 1) +
    scale_fill_manual(values=c(NA))