[R] Function calling a function, column name not passed properly

[David Winsemius]

> On Dec 1, 2015, at 2:57 PM, John Sorkin <jsorkin at grecc.umaryland.edu> wrote:
> 
> I am trying to write a function that calls a function. The first call to SmallFn works without any problem, printing both the passed data and the column Wstscr. The second call does not work (error, Error in d[, column] : subscript out of bounds). 
> 
> The first call shows what I am trying to do with the second call. I am passing to the outer function doit12 the beginning of the name of the column that I want to access (Wst). doit12 creates the full name of the column (Wstscr) by using varxx <- deparse(susbstitute(variable)) and varscr <- paste(varxx,"scr",sep=""). I can access the column in doit12 as seen by the results of   print(data[,varscr]).
> 
> SmallFn works when it is called using SmallFn(Wstscr,data), but fails when called with SmallFn(varscr,data). I don't understand why the second call fails. varscr was shown to represent Wstscr.
> 
> Please tell my why the second call is not working, please put me out of one-full day of misery!

It’s telling you there is no column in that dataframe with the name “varscr”.

— 
David.


> Thank you,
> John
> 
> 
> 
> 
> mydata <- cbind(   patient_id=c(10163,10987,19882,19899,20104,20105,20167,20318,20338,20392),
>                   Wstscr=c(139.00,NA,101.80,103.00,76.40,116.00,139.80,111.31,NA,150.00))            
> mydata     
> 
> doit12 <-function(variable,data) {
> 
>  varxx <- deparse(substitute(variable))
>  cat("varxx created from first deparse substitute=",varxx,"\n")
>  varscr <- paste(varxx,"scr",sep="")
>  cat("1varscr=",varscr,"\n")
>  cat("Data inside doit12\n")
>  print(data)
>  cat("Print the Wstscr column of data. varscr created using paste after deparse substitute\n")
>  print(data[,varscr])
>  cat("\n\n")
> 
>  SmallFn <- function(v,d) {
>    cat("\nInside SmallFn\n")
>    zz <-match.call()
>    column <- deparse(substitute(v))
>    cat("column=",column,"\n")
>    cat("The results of match.call\n")
>    print(zz)
>    print("Hello world!")
>    print(d)
>    print(d[,column])
>  }
>  SmallFn(Wstscr,data)
>  SmallFn(varscr,data)
> }
> doit12(Wst,mydata)
> John David Sorkin M.D., Ph.D.
> Professor of Medicine
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing) 
> 
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