Consider the following two ways of stair steps plotting:
plo <- function(ty = 2, steps = 200){
old.par <- par(mfrow = c(2, 1))
x <- seq(1, 100, length = steps)
y <- seq(1, 10, length = steps)
plot(x, y, type = "s", lty = ty, main = "Stair steps")
x <- rep(x, each = 2)[-1]
y <- rep(y, each = 2)[-2*steps]
plot(x, y, type = "l", lty = ty, main = "Line steps")
par(old.par)
}
This shows a problem with 'type = "s"' combined with "lty
= "; the lines
look solid no matter what lty is set to, if the steps are small enough.
Is this intentional, and if so, why? This bit me when I tried to plot
empirical cdfs with the 'type = "s"' method; some curves were
impossible
to distinguish.
Btw, I checked 'plot.survfit', and it uses the second method, probably
of
this reason.
G?ran
---
G?ran Brostr?m tel: +46 90 786 5223
Department of Statistics fax: +46 90 786 6614
Ume? University http://www.stat.umu.se/egna/gb/
SE-90187 Ume?, Sweden e-mail: gb at stat.umu.se