colour <- c("red", "green", "blue", "yellow")
qplot(1:4, 1:4, fill = colour, geom = "tile")
qplot(1:4, 1:4, fill = colour, geom = "tile") + scale_fill_identity()
# To get a legend guide, you also need to supply labels, and specify
# guide = "legend"
qplot(1:4, 1:4, fill = colour, geom = "tile") +
scale_fill_identity("trt", labels = letters[1:4], breaks = colour,
guide = "legend")
# cyl scaled to appropriate size
qplot(mpg, wt, data = mtcars, size = cyl)
# cyl used as point size
qplot(mpg, wt, data = mtcars, size = cyl) + scale_size_identity()
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