[R] making scatter plot points fill semi-transparent

hi all, i have a simple scatter plot, and i'd like to make it so the scatter plot colors are slightly transparent. i see in a previous post that someone mentioned the "alpha" parameter, but i am not sure how it can be used with the 'plot' function [*]. for example, suppose i have: plot(mydata$co

[R] plotting points in random but different colors based on condition

hi all, suppose I have a file with several columns, and I want to plot all points that meet a certain condition (i.e. all points in columns A and B that have a value greater than such and such in column C of the data) in a new but random color. That is, I want all these points to be colored diffe