[R] Return a list

[Wacek Kusnierczyk]

Bert Gunter wrote:
> But why do this? Just leave the (preferably named) variables as list
> components and work with them there.
>
> 1. ?comment tells you how to add a comment attribute to the list for self
> documentation (what were the components? how are they related? etc.)
>
> 2. ?with  shows you how to access the components of the list individually in
> the "usual" way.
>
> 3. ?lapply and friends shows you how to "loop" over list components .
>
> etc.
>
> Cheers,
> Bert
>
> Bert Gunter 
> Genentech  
>
>   
it depends on what the original author wanted.

with constructs a new environment, and all assignments, if any, made in
the expression evaluated within with are invisible to the outside
(unless one plays with environments, again):

x = 1:10
a = 3
with(test(), { x[1:3] = c(a,b,c); x = x+d; a = a + 1 })
x # still 1:10, whatever test returns
a # still 3. whatever test returns

if the author wanted the values included in the list to be visible and
accessible by simple names, and used in assignments in a larger part of
code, using with might be inconvenient.
it does not mean that my solution below is a good one, it's just a quick
fix.  i wouldn't do that in myself, it's badly non-functional ;)

vQ


>>   
>>     
>>> I have several output variables which I give back with the list command.
>>>
>>> test <- function	{return(list(a,b,c,d,e,f,g,...))}
>>>
>>> After the usage of the function I want to assign the variables to the
>>>       
> output variables.
>   
>>> result <- test()
>>>
>>> a <- result$a
>>> b <- result$b
>>> c <- result$c
>>> d <- result$d
>>> ...
>>>
>>> is there a more elegant way to assign these variables, without writing
>>>       
> them all down?
>   
>>>     
>>>       
>
> arguably ugly and risky, but simple:
>
> for (name in names(result)) assign(name, result[[name]])
>
> (note, for this to work you actually need to name the components of the
> returned list: return(list(a=a,b=b,...)))
>
> vQ
>
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> ______________________________________________
> 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.
>   


-- 
-------------------------------------------------------------------------------
Wacek Kusnierczyk, MD PhD

Email: waku at idi.ntnu.no
Phone: +47 73591875, +47 72574609

Department of Computer and Information Science (IDI)
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Norwegian University of Science and Technology (NTNU)
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