change both legend titles in a ggplot with two legends

Question

I have two legends on my ggplot with two different legend titles (automatically created from ggplot()). Now, I want to change this legend titles. + labs(

Answer 1

If I understood your point correctly, you can simply use + labs(shape = "shape legend title", colour = "colour legend title")

Answer 2

Here is an example using the iris dataset:

data(iris)
ggplot(iris, aes(x=Sepal.Length, y=Sepal.Width)) +
    geom_point(aes(shape=Species, colour=Petal.Width)) + 
    scale_colour_gradient() +
    labs(shape="Species label", colour="Petal width label")

You specify the labels using labs(), with each scale separately specified, i.e. labs(shape="Species label", colour="Petal width label").