'at' parameter in mtext(.., adj=0, outer=T) (PR#396)

[Prof Brian D Ripley]

On Mon, 10 Jan 2000 john.maindonald@anu.edu.au wrote:

> Depending on the setting of par()$usr, 
> the 'at' setting in mtext(.., adj=0, outer=T) may cause the
> text to appear in an anomalous position (e. g. in the first
> instance below, at the left of the plot region rather than
> at 'at=0' in the figure region), or the text may not appear
> at all.
> 
> If one does not set the 'at' parameter the text appears
> (with 'adj=0') on the far left of the plot region.  I assume
> this is also anomalous; at all events it is the behaviour
> that I wished to circumvent.

I am afraid this is documentation confusion. There are no user
coordinates in the outer margins, and at works like adj if outer=TRUE.
Indeed the example

mtext(side=1,line=0.5,"Outer text",outer=T, adj=0)

does work correctly for me: specifying adj=0 means put it at the extreme
left, adj=1 at the extreme right, and adj=0 to centre it (on the
display region, not the figure region).

I will re-write the documentation.

> 
> The function plot.test() demonstrates the behaviour:
> 
> plot.test <-
> function(xval=0:4, pos=NULL){
> oldpar<-par(oma=c(2,0,0,0))
> on.exit(par(oldpar))
> plot(xval,xval)
> if(is.null(pos))pos<-min(xval)
> print(pos)
> print(par()$usr)
> mtext(side=1,line=3.5,"Marginal text",adj=0,at=pos)
> mtext(side=1,line=0.5,"Outer text",outer=T, adj=0,at=min(xval))
> }
> 
> > plot.test(xval=0:4)  # "Outer text appears on left of the figure region
> [1] 0
> [1] -0.16  4.16 -0.16  4.16
> > plot.test(xval=20:24)  # "Outer text does not appear at all
> [1] 20
> [1] 19.84 24.16 19.84 24.16
> > # Check that at=0 does not work
> > plot.test(xval=20:24, pos=0)  # "Outer text does not appear at all
> [1] 0
> [1] 19.84 24.16 19.84 24.16
> >
> 
> 
> --please do not edit the information below--
> 
> Version:
>  platform = Windows
>  arch = x86
>  os = Win32
>  system = x86, Win32
>  status = 
>  major = 0
>  minor = 90.1
>  year = 1999
>  month = December
>  day = 15
>  language = R
> 
> Windows 9x 4.0 (build 1111)  B
> 
> Search Path:
>  .GlobalEnv, Autoloads, package:base
> 
> John Maindonald               email : john.maindonald@anu.edu.au        
> Statistical Consulting Unit,  phone : (6249)3998        
> c/o CMA, SMS,                 fax   : (6249)5549  
> John Dedman Mathematical Sciences Building
> Australian National University
> Canberra ACT 0200
> Australia
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-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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