xaxp and yaxp

Arne Mueller wrote:

Hello,

I'm new to R, and I'm trying to set the number of tickmarks for a plot
using xaxp, but R seems to ignore this setting completely. Maybe you've
an idea what I'm doing wrong. I'm using R 1.4.1, and here's hat I'm
doing:

d[,'seq']

[1] 28913 16323 13922  6237  4257  3881  4100  3781  2694  2064  1769
1550
[13]  1539   480

d[,'scop.dup.rate']

[1] 97.7 95.3 95.3 88.5 84.6 84.6 84.7 82.8 71.5 74.9 74.9 71.2 67.8
54.9

plot(d[,'seq'], d[,'scop.dup.rate'], col="red", pch=22, bg='red', cex=1.5, xlim = c(0,30000), ylim=c(20,100))

tick marks are placed at 0,5000, ... 30000 for the xaxis.

now I'd like to have more tickmarks

plot(d[,'seq'], d[,'scop.dup.rate'], col="red", pch=22, bg='red', cex=1.5, xlim = c(0,30000), ylim=c(20,100), xaxp=c(0,30000,13))

tickmarks are set the same way as above.

Also par(xaxp=c(0,30000,13)) does not change anything ... :-(

I'd like to have 13 tick marks on the x-axis including the extreme ones
(0 and 30000).

I'm not sure whether I realy understand what xaxp is doing, so I thought
it may need the interval:

par(xaxp=c(0,30000,2500))

hm, but this doesn't change anything either :-(

In your case you should set the tickmarks manually using axis(), e.g.:

 plot(..., xaxt="n")
 axis(1, at=seq(0, 30000, length=13)

If you don't specify the loactions manually the function pretty() will
be used in principle.


Uwe Ligges