how to control ticks in plots with yasp or xasp

Sat, Oct 8, 2005 9:17 AM

Hi, sorry about the bad syntax, though the right syntax would not  
have worked either, according to your tests (Mark, Brian, Peter).

Anyway it is too finicky, I will draw them myself. For instance,

plot(1:100, xaxt="n")
par(xaxp=c(0, 100, 10))  # the value is reset at each plot
axis(1)

Placed tick marks at intervals at 0, 10, ..., 100, as expected, but  
did not place a label under 100...

Thanks for the answers, usufull as always,

Denis


Le 05-10-08 ?? 11:58, Marc Schwartz a ??crit :

On Sat, 2005-10-08 at 16:37 +0100, Prof Brian Ripley wrote:

On Sat, 8 Oct 2005, Marc Schwartz wrote:

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")?

In any case, (0, 100, 10) is invalid syntax, and c(0, 100, 10) is  
needed.

Indeed.

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.

Really?  Try

plot(1:100, xaxt="n")
par(xaxp=c(0, 50, 5))  # the value is reset at each plot
axis(1)

for how it works (but not inline, which is probably a bug).

Ah....I had not thought about that 'par'ticular combination...  ;-)

Hence, not R.O.  So it must be used _after_ a plot call, which makes
sense.

I had reached for my copy of Paul's book and on page 96 (last  
paragraph
in section 3.4.5 on Axes), he suggests using the approach I elucidate
below with axTicks(). I thought he might have some other ideas and  
that
I was missing something. This is also referenced on page 70, third
paragraph in section 3.2.5 on Axes.

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.

That is usually as easy.

Agreed.

Thanks,

Marc

how to control ticks in plots with yasp or xasp

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