R: Passing parameters from a wrapper function to internal functions

Question

I am not surprised that this function doesn't work, but I cannot quite understand why.

computeMeans <- function(data,dv,fun) {
    x <- with(data,aggregate(dv,
        list(
            method=method,
            hypo=hypothesis,
            pre.group=pre.group,
            pre.smooth=pre.smooth
        ),
        fun ) )
    return(x)
}

computeMeans(df.basic,dprime,mean)

Where df.basic is a dataframe with factors method, hypothesis, etc, and several dependent variables (and I specify one with the dv parameter, dprime).

I have multiple dependent variables and several dataframes all of the same form, so I wanted to write this little function to keep things "simple". The error I get is:

Error in aggregate(dv, list(method = method, hypo = hypothesis, 
pre.group = pre.group,  : 
    object 'dprime' not found

But dprime does exist in df.basic, which is referenced with with(). Can anyone explain the problem? Thank you!

EDIT: This is the R programming language. http://www.r-project.org/

Answer 1

Although dprime exists in df.basic, when you call it at computeMeans it has no idea what you are referring to, unless you explicitly reference it.

computeMeans(df.basic,df.basic$dprime,mean)

will work.