[R] couldn't find function "..."

[Thomas Lumley]

On Wed, 5 Jul 2000, Steve Arthur wrote:

> Hi,
> 
> R 1.0.1, on Linux(mandrake/RedHat).
> 
> I am trying to write my first function using R and I need help figuring
> out the error I have indicated in the Subject line above.  The purpose
> of the function is not to "wow" anyone, but just to serve as a stepping
> stone so that I might write more complicated functions in the future.
> 
> First I created my function named "CIfunc" and saved into the current
> directory using the "save" command.
> 
> function(Mean, SD, N, Sig) {
> 
>    if (N > 30) { Zscore <- pnorm(Sig)} else {Zscore <- pt(Sig,N-1)}
>    Zscore
> 
>    UpperCI <- Mean + Zscore * SD / sqrt(N)
>    UpperCI
> 
>    LowerCI <- Mean - Zscore * SD / sqrt(N)
>    LowerCI
> 
> }
> 
> ...with no error.
> 
> Next I write the function call "testcall":
> 
> testcall <- call('CIfunc', prescan10$F532Mean, prescan10$F532SD,
> prescan10$FPixels, 0.95)
> 
> ...with no error.
> 
> testcall CIfunc(c(189, 238, 363, 869, 585, 350, 3624, 290, 436, 517),
> c(63, 58, 66, 127, 78, 46, 1452, 72, 83, 55), c(120, 120, 120, 120, 120,
> 120, 120, 120, 120, 120), 0.95)
> 
> But when I try to evaluate the function "CIfunc":
> 
> eval(testcall)
> 
> I get the error:
> 
> "Error in eval(expr, envir, enclos) : couldn't find function "CIfunc""
> 
> As I understand it, I saved the "CIfunc" in the directory I opened R from.
> 
> Do I need to set an environment variable to use functions in R?
> 

Unless you're trying to do something very complicated that I don't
understand this is a lot simpler than you're making it.

You don't have to write the function to a file. You don't need to use
call(), and you don't need eval().

You just want to type

CIfunc(prescan10$F532Mean, prescan10$F532SD, prescan10$FPixels, 0.95)


It's not clear why your function didn't work, but I suspect it's what
Peter Dalgaard suggested.  You need to have the function defined in the
workspace -- having it on disk doesn't help at all.

The point of call() and eval() is to allow functions to manipulate other
functions and expressions, which is an important part of the language,
but probably not an ideal subject for your first function. :)


	-thomas

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