[R] scripting/littler: How to call function named iteratively (`f1`, `f2`, …)?

[Eik Vettorazzi]

Hi Paul,
how about this
for (i in 1:2) { print( do.call(paste("f",i,sep=""),list(2, 3) )) }

or using get
for (i in 1:2) { print( get(paste("f",i,sep=""))(2, 3) ) }

cheers

Am 29.07.2011 15:28, schrieb Paul Menzel:
> Dear R folks,
> 
> 
> wanting to compare different implementations of a solution I want to
> script it to iterate over the different implementations. Is there a way
> to do this in the R shell/command line?
> 
>         $ more /tmp/iterf.r
>         f1 <- function(n = 100000,
>                        l = 100000)
>         {
>            z = n + l
>         }
>         
>         f2 <- function(n = 100000,
>                        l = 100000)
>         {
>            z = 2 * (n + l)
>         }
> 
> I tried the following, but it of course does not work.
> 
>         > source("/tmp/iterf.r")
>         > print(f1(2,3))
>         [1] 5
>         > print(f2(2,3))
>         [1] 10
>         > for (i in 1:2) { print( fi(2, 3) ) }
>         Fehler in print(fi(2, 3)) : konnte Funktion "fi" nicht finden
> 
> Can I compose a command from values of variables?
> 
> Going on I tried to script that using the `r` from the package `littler`
> [1]. Unfortunately because of the required quotes "" for the command
> `source()` I am not able to expand the variable.
> 
>         $ for i in $(seq 2); do r -e "print($i)" ; done
>         [1] 1
>         [1] 2
>         $ for i in $(seq 2); do r -e 'source("/tmp/iterf.r"); print(1)' ; done
>         [1] 1
>         [1] 1
>         $ # The next example does not work, because the variable $i does not get expanded when surrounded by ''.
>         $ for i in $(seq 2); do r -e 'source("/tmp/iterf.r"); print(f$i(2, 3))' ; done
>         Fehler in print(f$i(2, 3)) : Objekt 'f' nicht gefunden
>         Ausführung angehalten
>         Fehler in print(f$i(2, 3)) : Objekt 'f' nicht gefunden
>         Ausführung angehalten
> 
> Searching for »iterating function names« with rseek.org did give any
> good results. I also read the appendix in the introduction to R [2], but
> this did not have anything regarding to this either.
> 
> Is there a way to script this?
> 
> 
> Thanks,
> 
> Paul
> 
> 
> [1] http://packages.debian.org/sid/littler
> [2] http://cran.r-project.org/doc/manuals/R-intro.html#Scripting-with-R
> 
> 
> 
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-- 
Eik Vettorazzi
Institut für Medizinische Biometrie und Epidemiologie
Universitätsklinikum Hamburg-Eppendorf

Martinistr. 52
20246 Hamburg

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