See ggplot2::scale_alpha() for details.
scale_pattern_alpha_continuous(..., range = c(0.1, 1))scale_pattern_alpha_discrete(...)
scale_pattern_alpha_ordinal(..., range = c(0.1, 1))
Other arguments passed on to continuous_scale(), binned_scale,
or discrete_scale() as appropriate, to control name, limits,
breaks, labels and so forth.
Output range of alpha values. Must lie between 0 and 1.