# [R] How to generate 'minor' ticks in lattice (qqmath)

Gabor Grothendieck ggrothendieck at gmail.com
Tue Jan 23 16:44:19 CET 2007

```Another approach is shown in the last example at the bottom of:

library(zoo)
?xyplot.zoo

On 1/23/07, Helmut Schütz <helmut.schuetz at bebac.at> wrote:
> Dear group,
>
> I tried to generate labels for every second tick in lattice (qqmath).
> Version: 0.14-16
> Date: 2006/12/01
>
> R version 2.4.1 (2006-12-18)
>
> An example:
>
> library(lattice)
> numy=100
> y=runif(numy,min=0,max=1)
> sig=0.05
> numsig=length(which(y<sig))
>
> tck.no=11 # number of ticks
> tcks=1:tck.no
> labl=as.character(0.1*tcks-0.1) # label for all ticks
> labl[seq(2,tck.no-1,2)]="" # delete every second label
> nums=seq(0,(tck.no-1)/10,(tck.no-1)/100)
>
> qqmath(y,distribution=qunif,
>  prepanel=NULL,
>  panel=function(x)
>    {
>    panel.abline(c(0,1),lty=2)
>
> panel.polygon(c(0,0,numsig/numy,numsig/numy,0),c(0,sig,sig,0,0),lwd=0.75)
>    panel.qqmath(x,distribution=qunif,col=1)
>    },
>    scales=list(
>      tck=c(1,0),
>      x=list(at=nums,labels=labl),
>      cex=0.8),
>    xlab=paste("uniform [0,1] quantiles"),
>    ylab="runif [0,1]",
>    min=0,max=1)
>
> Two questions:
> 1. How do I define the same labels for the second (left) axis (I suspect
> a second dimension in scales(list(x=list...) would do the job, but I
> haven't been able finding out, how...
> 2. Is there any alternative to obtain minor ticks in lattice like
> "minor.ticks" in Hmisc?
>
> Best regards,
> Helmut
>
> --
> Helmut Schütz
> BEBAC
> Consultancy Services for Bioequivalence and Bioavailability Studies
> Neubaugasse 36/11
> 1070 Vienna/Austria
> tel/fax +43 1 2311746
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>
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