Try this

data <- eval(parse(text=paste(study, level, ".", population, sep="")))

Jean

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dbateman wrote on 08/31/2011 17:44:44:

I have several datasets that come from different studies (fv02 and fv03), 
they represent different levels (patients and lesions), and they have 
different patient populations (itt, mitt, mitt3).  I wanted to write some 
code that would pass my three requirements into a function I wrote, 
produce the output, but not have to require me to also pass a unique plot 
title or output filename for each function call.  The title and file name 
would be created in the function according to the three input parameters.

My datasets are named like this (all six are repeated for "fv03" in place 
of "fv02"):
   fv02patients.itt
   fv02patients.mitt
   fv02patients.mitt3
   fv02lesions.itt
   fv02lesions.mitt
   fv02lesions.mitt3

Taking the first dataset as an example, I currently have this code:
   study="fv02"
   level="patients"
   population="itt"
   noquote(paste(study,level,".",population,sep=""))

This produces the desired fv02patients.itt, but it is just an unquoted 
character string rather than a data frame.

Here is a condensed look at my function:

waterfall=function(data,title,file)
{       barplot(height=data$brpercent,main=paste("Best Change in Tumor 
Volume\n",title)),
        savePlot(filename=file,type="pdf")
}
waterfall(data=fv02patients.itt,title="EC-FV-02 ITT
Patients",file=fv02_itt_patients_waterfall")


It may be easier to leave it the way I have it, but if this is possible, I
would still be interested in knowing.

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