R help - Apr 2008 - pdf() and histogram() in function call

Here is a function I wrote. It runs no problem, but generate empty pdf
   files.

   I can't find what is the problem.


   create.pdf<- function(x, dir)
    {
     dir.create(dir, showWarnings = FALSE)
     plist<- c("a", "b" , "c", "d")

     for(j in plist)
     {

      filedir<- paste(dir, "/", j, ".pdf",
sep="")

      form1<- as.formula(paste("~ ", j, " | var1",
sep=" "))
      form2<- as.formula(paste("~ ", j, " | var2",
sep=" "))
      form3<- as.formula(paste("~ ", j, " | var3",
sep=" "))
      pdf(filedir)

      histogram(form1,data=x,type="count", xlab=j,main="Histogram
conditioned
   on the levels of var1")
      histogram(form2,data=x, type="count",xlab=j,main="Histogram
conditioned
   on the levels of var2")
      histogram(form3, data=x, type="count", xlab=j,
main="Histogram
   conditioned on the levels of var3" )

      dev.off()
     }


    }


   I have tried to find the problem, but no luck!  Seriously need HELP! Thanks.

     _________________________________________________________________

   Be a better friend, newshound, and know-it-all with Yahoo! Mobile. [1]Try it
   now.

References

   1.
http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

Read FAQ 7.22

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of qian z
> Sent: Wednesday, April 23, 2008 10:49 AM
> To: r-help at r-project.org
> Subject: [R] pdf() and histogram() in function call
> 
> 
>    Here is a function I wrote. It runs no problem, but 
> generate empty pdf
>    files.
> 
>    I can't find what is the problem.
> 
> 
>    create.pdf<- function(x, dir)
>     {
>      dir.create(dir, showWarnings = FALSE)
>      plist<- c("a", "b" , "c",
"d")
> 
>      for(j in plist)
>      {
> 
>       filedir<- paste(dir, "/", j, ".pdf",
sep="")
> 
>       form1<- as.formula(paste("~ ", j, " | var1",
sep=" "))
>       form2<- as.formula(paste("~ ", j, " | var2",
sep=" "))
>       form3<- as.formula(paste("~ ", j, " | var3",
sep=" "))
>       pdf(filedir)
> 
>       histogram(form1,data=x,type="count", 
> xlab=j,main="Histogram conditioned
>    on the levels of var1")
>       histogram(form2,data=x, 
> type="count",xlab=j,main="Histogram conditioned
>    on the levels of var2")
>       histogram(form3, data=x, type="count", xlab=j,
main="Histogram
>    conditioned on the levels of var3" )
> 
>       dev.off()
>      }
> 
> 
>     }
> 
> 
>    I have tried to find the problem, but no luck!  Seriously 
> need HELP! Thanks.
> 
>      _________________________________________________________________
> 
>    Be a better friend, newshound, and know-it-all with Yahoo! 
> Mobile. [1]Try it
>    now.
> 
> References
> 
>    1. 
> http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_yl
t=Ahu06i62sR8HDtDypao8Wcj9tAcJ
> ______________________________________________
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> PLEASE do read the posting guide 
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> and provide commented, minimal, self-contained, reproducible code.
>