[R] export the graphical result of bwplot()

[BIBIS, Garnier, Christophe]

Dear all,

Maybe somebody can help me to understand my problem:

Inside a R script, I try to export the graphic results of 'bwplot' in some
jpeg files.

The data source ('main') is a mix of numeric and factor values 
the "analysis_bwplot()" contains the loops (i and j) and calls the
"analysis_var_var_bwplot()" method.
"analysis_var_var_bwplot()" uses bwplot() to plot into a file (name n)

If i run the script, i receive some error messages (see below) and the
result files are always empty.
But if i manually run the commands of the method
"analysis_var_var_bwplot()", it exports the jpeg file as expected.

Curiously, i have a mix of numeric and factor data and it always recognize
some "numeric" data (in the "analysis_var_var_bwplot()" method)


Has somebody an idea?


Thanks,
Christophe



---ERROR MESSAGES--------------------------------------------

> analysis_bwplot()

 warn = 1
[1] "bwplot_var1_var2.jpg"
[1] "mode: numeric numeric"
Warning in bwplot(var1 ~ var2) : x should be numeric
...

 warn = 2
[1] "bwplot_var21_var22.jpg"
[1] "mode: numeric numeric"
Error in bwplot(var1 ~ var2) : (converted from warning) x should be numeric
Execution halted

---CODE--------------------------------------------
library(RMySQL)
library(XML)
library(lattice)

...

analysis_var_var_bwplot <- function(var1 , var1name , var2 , var2name )
{
    n <- paste("bwplot_" , var1name , "_" , var2name , ".jpg" , sep="")
    print(n)

    print ( paste("mode:" , mode(var1) , mode(var2) ) )
    
    jpeg(file=n)
    bwplot(var1 ~ var2 )
    dev.off()      

}

analysis_bwplot <- function()
  {
    length <- length(main)
    names <- names(main)

    ow <- options("warn")
    
    for (i in 1:length)  
      {

        options(warn = i )
        cat ("\n warn =" , i , "\n" )
        
        for (j in i+1:length)
          {
            if ( j > length ) break

            x <- main[[i]]
            y <- main[[j]]
            
            variableiname <- names[i]
            variablejname <- names[j]

            analysis_var_var_bwplot (x , variableiname  ,y , variablejname )

          }

      }

    warnings()
    options(ow) #reset
    
  }





*************************************************************** 
Dr. Christophe Garnier 	E-Mail: 	cgarnier at ttz-bremerhaven.de 
TTZ Bremerhaven 	Tel: 	+49 (0) 471-4832 183 
 			Fax: 	+49 (0) 471-4832 129 
 			Mobile:  +49 (0) 163-494 48 77 
BIBIS (Bremerhavener Institut für biologische Informationssysteme)
Fischkai 1 27572 Bremerhaven 
<http://www.ttz-bremerhaven.de>