R help - Mar 2013 - Equivalent of deal in R?

HI, I'm looking for a function that does the same as deal() in MATLAB, i,e,
for an array x[1 2 3]
[a,b,c]=x;
such that
a=1, b=2, c=3

Does R have any functions similar to this?

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Maybe

x <- array(1:3)

for(i in seq_along(x)) {
  assign(letters[i], x[i])
}

but usually there is no need for this kind of thing. Why do you want to do that?

Best,
Ista

On Thu, Mar 14, 2013 at 1:17 PM, Sahana Srinivasan
<sahanasrinivasan.91 at gmail.com> wrote:
> HI, I'm looking for a function that does the same as deal() in MATLAB,
i,e,
> for an array x[1 2 3]
> [a,b,c]=x;
> such that
> a=1, b=2, c=3
>
> Does R have any functions similar to this?
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.

On Mar 14, 2013, at 12:17 PM, Sahana Srinivasan <sahanasrinivasan.91 at
gmail.com> wrote:
> HI, I'm looking for a function that does the same as deal() in MATLAB,
i,e,
> for an array x[1 2 3]
> [a,b,c]=x;
> such that
> a=1, b=2, c=3
> 
> Does R have any functions similar to this?


There are various R/MATLAB references floating around, one being:

  http://cran.r-project.org/doc/contrib/Hiebeler-matlabR.pdf

A quick search suggests that there is no parallel for 'deal'. In
actuality, splitting up an array/vector in this manner would be somewhat
"un-R-like", where the general paradigm is to take a "whole
object" approach and process/manipulate R objects in their entirety, taking
advantage of R's innate vectorized approach to such things.

That being said, the ?assign function would take arguments of an R object and a
name and assign the object to the name. Since assign() is not vectorized (which
is arguably a hint), you would need to use a looping approach, perhaps along
these lines:


deal <- function(x, Vars) {
  for (i in seq(along = x)) 
    assign(Vars[i], x[i], envir = parent.frame())
}

This will take an object 'x' and assign the value(s) of x to the name(s)
contained in 'Vars'. It will assign the value(s) in the calling
environment of the function. Thus:
> ls()
[1] "deal"

deal(c(1, 2, 3), c("a", "b", "c"))
> ls()
[1] "a"    "b"    "c"    "deal"
> a
[1] 1
> b
[1] 2
> c
[1] 3


I did not include any error checking, but you would want to make sure that
length(x) == length(Vars) within the function.

I would however, urge you to reconsider what you are doing and take advantage of
R's philosophy and therefore, strengths. It may be that coercing your source
vector to a list would serve you well.

Regards,

Marc Schwartz

I think that the better approach in R, if you really need to do this, is to
convert your array to a list, assign the names to the list, then attach the
list to the search path so you can access the variables by name.  For
example:
> x <- c(1,2,3)
> x2 <- as.list(x)
> names(x2) <- c('a','b','c')
> attach(x2)
> a
[1] 1
> b
[1] 2
> c
[1] 3
> detach()
Or you can do most of the dirty work in 1 line:
> attach( setNames( as.list(x), c('a','b','c') ) )
> a
[1] 1
> b
[1] 2
> c
[1] 3
> detach()
> a
Error: object 'a' not found
>

This gives all the advantages of being able to access the different pieces
by the variable names that you want without cluttering up the global
workspace.
Just be careful that you don't have other variables of the same name
already in the global environment.  If you do then using functions like
with or within will work better than attaching.





On Thu, Mar 14, 2013 at 11:17 AM, Sahana Srinivasan <
sahanasrinivasan.91@gmail.com> wrote:
> HI, I'm looking for a function that does the same as deal() in MATLAB,
i,e,
> for an array x[1 2 3]
> [a,b,c]=x;
> such that
> a=1, b=2, c=3
>
> Does R have any functions similar to this?
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>


-- 
Gregory (Greg) L. Snow Ph.D.
538280@gmail.com

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