[R] impose points on lattice plot

[Sundar Dorai-Raj]

Luis Ridao Cruz said the following on 3/27/2007 6:15 AM:
> R-help,
> 
> I'm using the lattice package to plot 2 variables (vekt ~ aldur)
> conditioned to a third (kyn * 2 categories).
> 
> I use the following:
> 
> xyplot(vekt ~ aldur|kyn, , data = sexSu)
> 
> 
> I want to superimpose the average(vekt) by 'aldur' 
> conditioned to kyn by using something like:
> 
> xyplot(vekt~aldur|kyn, subset = aldur <= 12
> , data = sexSu, panel = function(x, y)
>        {
>        panel.xyplot(x, y)
>        panel.points(x,mean(y),col=2,cex=2 )
>        }) 
> 
> 
> but th output is just a horozontal line ( the average of 'vekt')
> in both panels I guess)
> 
> How can be done?
> 
> 


An working example would be nice. But here's one possible solution if I 
understand your question correctly:

xyplot(vekt~aldur|kyn, subset = aldur <= 12
, data = sexSu, panel = function(x, y)
        {
        panel.xyplot(x, y)
        mx <- sort(unique(x))
        my <- tapply(y, x, mean)
        o <- order(mx)
        panel.points(mx[o],my[o],col=2,cex=2 )
        })


but th output

> Thanks in advance
> 
> 
>> version
>                _                           
> platform       i386-pc-mingw32             
> arch           i386                        
> os             mingw32                     
> system         i386, mingw32               
> status                                     
> major          2                           
> minor          4.1                         
> year           2006                        
> month          12                          
> day            18                          
> svn rev        40228                       
> language       R                           
> version.string R version 2.4.1 (2006-12-18)
> 
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