scale_size
scales area, scale_radius
scales radius. The size
aesthetic is most commonly used for points and text, and humans perceive
the area of points (not their radius), so this provides for optimal
perception. scale_size_area
ensures that a value of 0 is mapped
to a size of 0.
scale_radius(name = waiver(), breaks = waiver(), labels = waiver(), limits = NULL, range = c(1, 6), trans = "identity", guide = "legend") scale_size(name = waiver(), breaks = waiver(), labels = waiver(), limits = NULL, range = c(1, 6), trans = "identity", guide = "legend") scale_size_area(..., max_size = 6)
name  The name of the scale. Used as axis or legend title. If


breaks  One of:

labels  One of:

limits  A numeric vector of length two providing limits of the scale.
Use 
range  a numeric vector of length 2 that specifies the minimum and maximum size of the plotting symbol after transformation. 
trans  Either the name of a transformation object, or the object itself. Builtin transformations include "asn", "atanh", "boxcox", "exp", "identity", "log", "log10", "log1p", "log2", "logit", "probability", "probit", "reciprocal", "reverse" and "sqrt". A transformation object bundles together a transform, it's inverse,
and methods for generating breaks and labels. Transformation objects
are defined in the scales package, and are called 
guide  Name of guide object, or object itself. 
...  Other arguments passed on to 
max_size  Size of largest points. 
scale_size_area
if you want 0 values to be mapped
to points with size 0.
p + scale_size("Highway mpg")p + scale_size(range = c(0, 10))# If you want zero value to have zero size, use scale_size_area: p + scale_size_area()# This is most useful when size is a count ggplot(mpg, aes(class, cyl)) + geom_count() + scale_size_area()# If you want to map size to radius (usually bad idea), use scale_radius p + scale_radius()