R help - May 2006 - error in color-labeling in plot.lm

I want to label groups of points in
the plot of residuals against predicted values 
generated by plot.lm().
 
Labelling the points by color
 
x<-1:15
y<-rnorm(15)
f<-factor(rep(c(1:3),each=5))
g<-glm(y~x)
plot(g,which=1,col=c(1,2,3)[f])
 

I receive the error message
 
Error in title(main, sub, xlab, ylab, line, outer, ...) : 
        graphical parameter "col" has the wrong length
 
How can I resolve the error?
 
 
 
Labelling by symbols works fine
 
plot(g,which=1,pch=c(1,2,3)[f])
 
And setting
 
par(mfrow=c(1,2))
 
before plotting, produces  the color plot without error
 
plot(g,which=1,col=c(1,2,3)[f])
 
 
 
Ulrich
 
platform       i386-pc-mingw32           
arch           i386                      
os             mingw32                   
system         i386, mingw32             
status                                   
major          2                         
minor          3.0                       
year           2006                      
month          04                        
day            24                        
svn rev        37909                     
language       R                         
version.string Version 2.3.0 (2006-04-24)


Ulrich Halekoh
Danish Institute of Agricultural Sciences
Unit of Statistics and Decision Analysis
8830 Tjele, Denmark
 

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On Mon, 8 May 2006, Ulrich Halekoh wrote:
> I want to label groups of points in
> the plot of residuals against predicted values
> generated by plot.lm().
>
> Labelling the points by color
>
> x<-1:15
> y<-rnorm(15)
> f<-factor(rep(c(1:3),each=5))
> g<-glm(y~x)
> plot(g,which=1,col=c(1,2,3)[f])
>
>
> I receive the error message
>
> Error in title(main, sub, xlab, ylab, line, outer, ...) :
>        graphical parameter "col" has the wrong length
>
> How can I resolve the error?
Well, the help does say


      ...: other parameters to be passed through to plotting functions.

and it really is unclear what you intended 'col' to refer to.  But as 
title() is not going to make use of it, it should accept it.  I'll see if I 
can adapt it suitably.

-- 
Brian D. Ripley,                  ripley at 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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595