ggplot-alpha-demo

library(ggplot2)

## Warning: package 'ggplot2' was built under R version 3.2.3

x_coord <- c(2,5,7,4,7,8,9,4,2,5,6)
y_coord <- c(1,7,3,0,7,4,7,6,3,2,4)
filter_var <-  c(1,1,1,1,1,1,0,0,0,0,0)

df <- data.frame(x_coord,y_coord, filter_var)

ggplot(df, aes(x=x_coord, y=y_coord)) +
  geom_point(data=df[df$filter_var==0,], alpha=0.2, size=10) +
  geom_point(data=df[df$filter_var==1,], alpha=0.8, size=10)