Change transparency of symbols in R function plotrix::polar.plot()

Question

Is there a simple way to control the transparency of the blue circles in the function below to control the overplotting.

library(plotrix)
polar.plot(1:5000, rnorm(5000,90,30), rp.type='s', point.col='blue')

I'm hoping for some transparency parameter, usually called alpha, between 0 and 1.

Answer 1

There are lots of ways to do this, but an easy one is using the rgb function. Here is an example with 50% transparency.

polar.plot(1:5000, rnorm(5000,90,30), rp.type='s', point.col=rgb(0,0,1, 0.5))