如果我想在使用下一个代码时在ggplot2中添加图例,我遇到了问题:
ggplot() +
geom_point(data = select, aes(x = Date, y = Netto), colour = "red") +
geom_point(data = select, aes(x = Date, y = First), colour = "blue") +
geom_point(data = select, aes(x = Date, y = Second), colour = "black")
我有三种不同的颜色,但我找不到如何在这个情节中添加一个图例。