R help - Nov 2008 - How do I generate multiple (similar) objects within R?

Hi,

I wonder if anyone knows how to generate a list of objects, e.g. ten 
vectors with names: vect1, vect2, ... , vect10.
My own idea was to use something like:

    for (i in 1:10)
    print(paste("vect", i,"<-NULL",sep=""))

but the result is:

"vect1<-NULL"
...
"vect10<-NULL"

and not

vect1<-NULL
...
vect10<-NULL

as I would like. Does anyone know?

An, again FAQ "How can I turn a string into a variable?" ....

Uwe Ligges



Nicklas Pettersson wrote:
> Hi,
> 
> I wonder if anyone knows how to generate a list of objects, e.g. ten 
> vectors with names: vect1, vect2, ... , vect10.
> My own idea was to use something like:
> 
>    for (i in 1:10)
>    print(paste("vect", i,"<-NULL",sep=""))
> 
> but the result is:
> 
> "vect1<-NULL"
> ...
> "vect10<-NULL"
> 
> and not
> 
> vect1<-NULL
> ...
> vect10<-NULL
> 
> as I would like. Does anyone know?
> 
> ______________________________________________
> 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.

'assign'

for (i in 1:10) assign(paste('vect', i, sep=''), NULL)

or use a 'list'

On Tue, Nov 18, 2008 at 12:58 PM, Nicklas Pettersson
<Nicklas.Pettersson at stat.su.se> wrote:
> Hi,
>
> I wonder if anyone knows how to generate a list of objects, e.g. ten
vectors
> with names: vect1, vect2, ... , vect10.
> My own idea was to use something like:
>
>   for (i in 1:10)
>   print(paste("vect", i,"<-NULL",sep=""))
>
> but the result is:
>
> "vect1<-NULL"
> ...
> "vect10<-NULL"
>
> and not
>
> vect1<-NULL
> ...
> vect10<-NULL
>
> as I would like. Does anyone know?
>
> ______________________________________________
> 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

Nicklas Pettersson <Nicklas.Pettersson <at> stat.su.se> writes:
> 
> Hi,
> 
> I wonder if anyone knows how to generate a list of objects, e.g. ten 
> vectors with names: vect1, vect2, ... , vect10.
> My own idea was to use something like:
> 
>     for (i in 1:10)
>     print(paste("vect",
i,"<-NULL",sep=""))
> 
  I think this is FAQ 7.21, "how can I turn a string into
a variable":

http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-can-I-turn-a-string-into-a-variable_003f

  cheers
    Ben Bolker

Nicklas Pettersson <Nicklas.Pettersson <at> stat.su.se> writes:
> I wonder if anyone knows how to generate a list of objects, e.g. ten 
> vectors with names: vect1, vect2, ... , vect10.
> My own idea was to use something like:
> 
>     for (i in 1:10)
>     print(paste("vect",
i,"<-NULL",sep=""))
> 
for (i in 1:10)
  eval(parse(text=paste("vect",
i,"<-NULL",sep="")))
ls()
 
But better use a list or vector for what you are trying to do. Note that 
the  "list of objects" is not exactly what you intended with your
example
(which otherwise is nice, because it shows clearly what did not work).

Dieter