[R] Plotting lines with equidistant points for identification

[Timo Schneider]

Dear R Gurus,

I would like to make a line-plot of a large data-set (>200 data-points)
for a document which will be printed in black and white. The plot will
contain 5 different lines. So i need a way to differentiate between the
lines. Since color is not an option i tried different line styles with
all sorts of "line-gap" or "dot dot dot" patterns. Since my plots are
rather small it is hard to get lines that look contiguous enough while
still being identifiable through their line style.

What I would like to have are lines that have symbols on top of them,
similar to what i get with plot(x,y,type='o'). The problem is that i
have to many data-points for that method, the symbols will just "melt
together", as in plot(seq(1,500), seq(1,500), type='o') - just one big
line.

What i want is to have a configurable number of symbols spread
equidistantly over the whole graph, regardless of the number or position
of data-points.

Does anyone have an idea how to achieve this?

Thanks,
Timo