Question

In R, the plot() function takes a pch argument that controls the appearance of the points in the plot. I’m making scatterplots with tens of thousands of points and prefer a small, but not too small dot. Basically, I find pch='.' to be too small, but pch=19 to be too fat. Is there something in the middle or some way to scale the dots down somehow?

Answer 1

Try the cex argument:

?par

• cex
  A numerical value giving the
  amount by which plotting text and
  symbols should be magnified relative
  to the default. Note that some
  graphics functions such as
  plot.default have an argument of this
  name which multiplies this graphical
  parameter, and some functions such as
  points accept a vector of values
  which are recycled. Other uses will
  take just the first value if a vector
  of length greater than one is
  supplied.