# NOT RUN { aes(x = mpg, y = wt) aes(mpg, wt) # You can also map aesthetics to functions of variables aes(x = mpg ^ 2, y = wt / cyl) # Or to constants aes(x = 1, colour = "smooth") # Aesthetic names are automatically standardised aes(col = x) aes(fg = x) aes(color = x) aes(colour = x) # aes() is passed to either ggplot() or specific layer. Aesthetics supplied # to ggplot() are used as defaults for every layer. ggplot(mpg, aes(displ, hwy)) + geom_point() ggplot(mpg) + geom_point(aes(displ, hwy)) # Tidy evaluation ---------------------------------------------------- # aes() automatically quotes all its arguments, so you need to use tidy # evaluation to create wrappers around ggplot2 pipelines. The # simplest case occurs when your wrapper takes dots: scatter_by <- function(data, ...) { ggplot(data) + geom_point(aes(...)) } scatter_by(mtcars, disp, drat) # If your wrapper has a more specific interface with named arguments, # you need "enquote and unquote": scatter_by <- function(data, x, y) { x <- enquo(x) y <- enquo(y) ggplot(data) + geom_point(aes(!!x, !!y)) } scatter_by(mtcars, disp, drat) # Note that users of your wrapper can use their own functions in the # quoted expressions and all will resolve as it should! cut3 <- function(x) cut_number(x, 3) scatter_by(mtcars, cut3(disp), drat) # }
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