[R] looping variable names

[Greg Snow]

It is not clear what you are trying to do, but you can have lists (or vectors) of functions and that should simplify what you are trying to do:

> trigfuns <- list( s=sin, c=cos, t=tan )
> trigfuns
$s
function (x)  .Primitive("sin")

$c
function (x)  .Primitive("cos")

$t
function (x)  .Primitive("tan")

> sapply( trigfuns, function(f) f(pi/3) )
        s         c         t 
0.8660254 0.5000000 1.7320508 
>

And you can write a function that creates and returns a function:

> tmpfun <- function(a,b){
+ force(a); force(b)
+ function(x) {a + b * x}
+ }
> 
> myfuns <- vector('list',10*10)
> dim(myfuns) <- c(10,10)
> for(i in 1:10) {
+   for(j in 1:10) { 
+ myfuns[[i,j]] <- tmpfun(i,j)
+   }
+ }
> 
> myfuns[[2,3]](1:10)
 [1]  5  8 11 14 17 20 23 26 29 32
> myfuns[[3,2]](1:10)
 [1]  5  7  9 11 13 15 17 19 21 23
>

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Alaios
> Sent: Thursday, February 03, 2011 3:49 AM
> To: hypermonkey22; Eik Vettorazzi
> Cc: r-help at r-project.org
> Subject: Re: [R] looping variable names
> 
> Hello I would like to ask you if I can use the same method but for
> functions. That means that I want not to assign some value but a
> function.
> So is it possible to try something like that:
> 
> for (i in 1:10)  for (j in 1:10)
> assign(paste("var",i,j,sep=""),myfunction)
> 
> 
> 
> I would like to thank you in advance for your help
> 
> best Regards
> Alexandros
> --- On Thu, 2/3/11, Eik Vettorazzi <E.Vettorazzi at uke.uni-hamburg.de>
> wrote:
> 
> > From: Eik Vettorazzi <E.Vettorazzi at uke.uni-hamburg.de>
> > Subject: Re: [R] looping variable names
> > To: "hypermonkey22" <jonmosco at gmail.com>
> > Cc: r-help at r-project.org
> > Date: Thursday, February 3, 2011, 10:34 AM
> > As Greg wrote, a list is in most
> > circumstances a better way to store
> > many objects.
> > But you can use 'assign' and 'get' to create and access
> > (global) variables
> >
> > #creation
> > for (i in 1:100) assign(paste("var",i,sep=""),rnorm(5))
> >
> > #access i-th variable
> > i<-15
> > get(paste("var",i,sep=""))
> >
> > hth.
> >
> > Am 02.02.2011 21:36, schrieb hypermonkey22:
> > >
> > > Hi all,
> > >
> > > I've been looking for a simple answer to the following
> > problem.
> > >
> > > Let's say that I can loop through, say, 100 values
> > that need to be assigned
> > > to, say, the variables var1:var100.
> > >
> > > Is there an elegant way to do this?
> > >
> > > I have seen one or two similar questions...but they
> > tend to be in more
> > > complicated contexts.
> > > Simple question, hopefully with a simple answer.
> > >
> > > Thanks very much!
> >
> >
> > --
> > Eik Vettorazzi
> > Institut für Medizinische Biometrie und Epidemiologie
> > Universitätsklinikum Hamburg-Eppendorf
> >
> > Martinistr. 52
> > 20246 Hamburg
> >
> > T ++49/40/7410-58243
> > F ++49/40/7410-57790
> >
> > ______________________________________________
> > R-help at r-project.org
> > mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> > and provide commented, minimal, self-contained,
> > reproducible code.
> >
> 
> 
> 
> 
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.