[R] xyplot and for loops

[Dave Atkins]

Thanks to Andy and Bert for setting me straight!  Explicitly printing the xyplot 
command takes care of the issue.  Just didn't dig quite far enough into the 
documentation.

cheers, Dave

apjaworski at mmm.com wrote:

> 
> 
> 
> 
> Dave,
> 
> I think inside the loop you have to explicitly "print" a trellis object,
> i.e.  say
> 
> print(yplot(tmp.df$y.tmp ~ tmp.df[,i]))
> 
> If you read the help page for xyplot, look under "Value".
> 
> Hope this helps,
> 
> Andy
> 
> __________________________________
> Andy Jaworski
> 518-1-01
> Process Laboratory
> 3M Corporate Research Laboratory
> -----
> E-mail: apjaworski at mmm.com
> Tel:  (651) 733-6092
> Fax:  (651) 736-3122
> 
> 
>                                                                            
>              Dave Atkins                                                   
>              <datkins at u.washin                                             
>              gton.edu>                                                  To 
>              Sent by:                  r-help at stat.math.ethz.ch            
>              r-help-bounces at st                                          cc 
>              at.math.ethz.ch                                               
>                                                                    Subject 
>                                        [R] xyplot and for loops            
>              05/04/2004 05:40                                              
>              PM                                                            
>                                                                            
>                                                                            
>                                                                            
>                                                                            
> 
> 
> 
> 
> 
> I'm attempting to use xyplot() within a for() loop to plot the relationship
> 
> between a DV and a series of predictor variables, split by 2 conditioning
> variables.  However, xyplot() does not "seem" to be recognized within the
> for()
> loop; I don't receive any error message, but nothing is plotted and a
> plotting
> device is not opened.  When I use the generic function plot(), everything
> works
> as expected.  I'm using R v1.9.0 and lattice v0.9-11.
> 
> Here's a trivial example:
> 
> ### create single outcome and two predictors
>  > y.tmp <- rnorm(20) ; x1.tmp <- rnorm(20) ; x2.tmp <- rnorm(20)
> ### combine into data.frame
>  > tmp.df <- data.frame(y.tmp, x1.tmp, x2.tmp)
>  > tmp.df
>          y.tmp       x1.tmp      x2.tmp
> 1   1.5022759 -0.150326662 -1.36627981
> [snip]
> 20  1.2667825 -0.070356651 -0.38433160
> 
> ### simple loop calling the columns of tmp.df to specify x variables
>  > for (i in 2:3){
> + plot(tmp.df$y.tmp ~ tmp.df[,i])
> + }
> ### works fine for plot()
> 
> ### try the same with xyplot()
>  > for (i in 2:3){
> + xyplot(tmp.df$y.tmp ~ tmp.df[,i])
> + }
> ### nothing happens; no error msg; no plotting device opened
> 
>  > xyplot(tmp.df$y.tmp ~ tmp.df[,2])
> ### without loop works fine and plots relationship of x1.tmp and y.tmp
> 
> Can someone see what I'm missing?  Any directions/pointers appreciated.
> 
> cheers, Dave
> datkins at u.washington.edu
> 
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