Add an option to change the alpha in ggmaplot()

[apcamargo]

Sometimes it is important to see the density of the points in a MA-plot. Usually, this is done by lowering the alpha of the points, which is not possible to do in ggmaplot() (in an easy way, at least). Adding an option to set point alpha in the ggmaplot() would be very useful.

[kassambara]

fixed now, thanks!

library(ggpubr)
data(diff_express)
# Default plot
ggmaplot(diff_express, main = expression("Group 1" %->% "Group 2"),
         fdr = 0.05, fc = 2, size = 0.4, 
         genenames = as.vector(diff_express$name),
         ggtheme = ggplot2::theme_minimal())

# Use alpha = 0.5
ggmaplot(diff_express, main = expression("Group 1" %->% "Group 2"),
         fdr = 0.05, fc = 2, size = 0.4, 
         genenames = as.vector(diff_express$name),
         ggtheme = ggplot2::theme_minimal(),
         alpha = 0.5
         )

^{Created on 2020-05-10 by the reprex package (v0.3.0.9001)}