[R] how to control ticks in plots with yasp or xasp

[Marc Schwartz]

On Sat, 2005-10-08 at 09:28 -0400, Denis Chabot wrote:
> Hi,
> 
> A few times I tried to control the number and position of tick marks  
> in plots with the yasp or xasp parameters. For example, a y axis was  
> drawn by default with tick marks at 0, 20, 40, 80 and 100. I tried to  
> get tick marks every 10 by adding
> 
> yasp=(0, 100, 10)
> 
> but this had no effect at all. I know I can draw the axis and tick  
> marks manually, but often this simple option would suffice if I could  
> understand how to make it work.
> 
> Thanks in advance,
> 
> Denis Chabot


I suspect that one problem you are having is that there is no
par("xasp") or par("yasp")....unless these are typos and you are trying
to use par("xaxp") and par("yaxp")?

There is an 'asp' argument to some of the plot functions (ie.
plot.default), but this has a different intention.

par("xaxp") and par("yaxp") are not listed as read only pars in ?par,
however, I cannot recall an instance where R does not overwrite the user
settings during the calculation of the axes, whether passed as arguments
to a plot function or set a priori via a par() call.

If you want explicit control over the tick marks, you will need to use
axis(), perhaps in combination with axTicks(), after using 'xaxt = "n"'
and/or 'yaxt = "n"' in the plot call, depending upon the circumstances.

HTH,

Marc Schwartz