R help - Aug 2010 - change object name within for loop

Hi,

I am writing a for loop that creates one object, say 'outn' on every  
round of the loop. I would like the name of each object to include the  
index of the loop as in, for example:

out1, out2, out3, ...

And I would like the naming of the object to take place automatically  
as the loop moves through?

Similarly, I would like to be able to call different objects (in1,  
in2, in3, ...) authomatically through the execution of the loop.

Is there a quick solution for this? Thank you for any help.

I apologize if this question has been addressed recently in this forum  
- I could not find an answer online.

Best,

Gon?alo

Gon?alo Ferraz wrote:
> Hi,
> 
> I am writing a for loop that creates one object, say 'outn' on
every
> round of the loop. I would like the name of each object to include the 
> index of the loop as in, for example:
> 
> out1, out2, out3, ...
> 
> And I would like the naming of the object to take place automatically as 
> the loop moves through?
Combine ?assign and ?paste, or better yet, avoid the use of this idiom
and store everything in a named list.  That way, you can use functions
like lapply to quickly work with your data, instead of resorting to
for loops for everything.
> 
> Similarly, I would like to be able to call different objects (in1, in2, 
> in3, ...) authomatically through the execution of the loop.
I don't know what that means. Possibly look at ?get.
> 
> Is there a quick solution for this? Thank you for any help.
> 
> I apologize if this question has been addressed recently in this forum - 
> I could not find an answer online.
> 
> Best,
> 
> Gon?alo
> 
> ______________________________________________
> 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.

The quick answer is to use a list.

The most simple:
outlist=list()
for (i in 1:10){
   outlist[[i]] = matrix(rnorm(100), 10, 10)
}

Same example, but with naming:
outlist=list()
for (i in 1:10){
   outlist[[i]] = data.frame(loop_number=i, matrix(rnorm(100), 10, 10))
}

now if you were to do
final_output=do.call('rbind', outlist)

You'd have something that you can probably work with.
str(final_output)

Lists are kind of weird, but they're worth exploring.  Remember that the
output of [ is a list and [[ returns the actual item.  So to get the third
data.frame you'd want to use
outlist[[3]]


2010/8/20 Gonçalo Ferraz <gferraz29@gmail.com>
> Hi,
>
> I am writing a for loop that creates one object, say 'outn' on
every round
> of the loop. I would like the name of each object to include the index of
> the loop as in, for example:
>
> out1, out2, out3, ...
>
> And I would like the naming of the object to take place automatically as
> the loop moves through?
>
> Similarly, I would like to be able to call different objects (in1, in2,
> in3, ...) authomatically through the execution of the loop.
>
> Is there a quick solution for this? Thank you for any help.
>
> I apologize if this question has been addressed recently in this forum - I
> could not find an answer online.
>
> Best,
>
> Gonçalo
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

On Aug 20, 2010, at 1:07 PM, Gon?alo Ferraz wrote:
> Hi,
>
> I am writing a for loop that creates one object, say 'outn' on
every
> round of the loop. I would like the name of each object to include  
> the index of the loop as in, for example:
>
> out1, out2, out3, ...
?assign
?paste
>
> And I would like the naming of the object to take place  
> automatically as the loop moves through?
>
> Similarly, I would like to be able to call different objects (in1,  
> in2, in3, ...) authomatically through the execution of the loop.
?get
?paste
>
> Is there a quick solution for this? Thank you for any help.
There are many worked examples in the archives.

>
> I apologize if this question has been addressed recently in this  
> forum - I could not find an answer online.
How did you search?
>
> Best,
>
> Gon?alo
-- 
David.