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Alpha-transparency scales are not tremendously useful, but can be a convenient way to visually down-weight less important observations. scale_alpha() is an alias for scale_alpha_continuous() since that is the most common use of alpha, and it saves a bit of typing.

Usage

scale_alpha(..., range = c(0.1, 1))

scale_alpha_continuous(..., range = c(0.1, 1))

scale_alpha_binned(..., range = c(0.1, 1))

scale_alpha_discrete(...)

scale_alpha_ordinal(..., range = c(0.1, 1))

Arguments

...

Other arguments passed on to continuous_scale(), binned_scale, or discrete_scale() as appropriate, to control name, limits, breaks, labels and so forth.

range

Output range of alpha values. Must lie between 0 and 1.

Examples

p <- ggplot(mpg, aes(displ, hwy)) +
  geom_point(aes(alpha = year))

p

p + scale_alpha("cylinders")

p + scale_alpha(range = c(0.4, 0.8))