Hi all,
I'm working with a bunch of large graphs, and stumbled across
something useful. Probably many of you know this, but I didn't and so
others might benefit.
Using pch="." speeds up plotting considerably over using symbols.
x <- runif(1000000)
y <- runif(1000000)
system.time(plot(x, y, pch="."))
user system elapsed
1.042 0.030 1.077
system.time(plot(x, y))
user system elapsed
37.865 0.033 38.122
If you have enough points, the result is also more legible.
Choice of which pch symbol makes a difference too, the default pch=1 being
the slowest of what I tried, but "." is by far the speediest.
system.time(plot(x, y, pch=0))
user system elapsed
11.191 0.011 11.270
system.time(plot(x, y, pch=1))
user system elapsed
38.024 0.008 38.245
system.time(plot(x, y, pch=2))
user system elapsed
14.140 0.027 14.270
system.time(plot(x, y, pch=3))
user system elapsed
15.696 0.011 15.799
system.time(plot(x, y, pch=4))
user system elapsed
18.770 0.007 18.888
This is a vanilla R session, 2.13.1 for x86_64-redhat-linux-gnu. I
haven't tried it on any other OS, but it's making my life a lot
smoother right now.
Sarah