R help - Nov 2008 - Transforming a list to a vector with associated levels

I am pretty sure that I came across a function that creates a vector of levels
from a list but I just can't remember.

Basically, I have something like
> t <- list(A=c(4,1,4),B=c(3,7,9,2))
> t
$A
[1] 4 1 4

$B
[1] 3 7 9 2

And I would like to get something like the following:
t levels
4 1
1 1
4 1
3 2
7 2
9 2
2 2

I tried unlist without success. I also do remember that there is a corresponding
function that create a list of t's according to the level from the matrix a
draw but no luck to remember it.

Thanks

--
Marco Blanchette, Ph.D.
Assistant Investigator
Stowers Institute for Medical Research
1000 East 50th St.

Kansas City, MO 64110

Tel: 816-926-4071
Cell: 816-726-8419
Fax: 816-926-2018

Dear Marco,
Try this:


# Data
t1 <- list(A=c(4,1,4),B=c(3,7,9,2))

# Processing
res=data.frame(
t1=do.call(c,t1),
levels=rep(c(1,2),do.call(c,lapply(t1,function(x) length(x))))
)
rownames(res)=NULL
res


HTH,

Jorge



On Tue, Nov 18, 2008 at 10:15 PM, Blanchette, Marco <
MAB@stowers-institute.org> wrote:
> I am pretty sure that I came across a function that creates a vector of
> levels from a list but I just can't remember.
>
> Basically, I have something like
>
> > t <- list(A=c(4,1,4),B=c(3,7,9,2))
> > t
> $A
> [1] 4 1 4
>
> $B
> [1] 3 7 9 2
>
> And I would like to get something like the following:
> t levels
> 4 1
> 1 1
> 4 1
> 3 2
> 7 2
> 9 2
> 2 2
>
> I tried unlist without success. I also do remember that there is a
> corresponding function that create a list of t's according to the level
from
> the matrix a draw but no luck to remember it.
>
> Thanks
>
> --
> Marco Blanchette, Ph.D.
> Assistant Investigator
> Stowers Institute for Medical Research
> 1000 East 50th St.
>
> Kansas City, MO 64110
>
> Tel: 816-926-4071
> Cell: 816-726-8419
> Fax: 816-926-2018
>
> ______________________________________________
> 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]]

My guess is that you are dimly remembering stack(.)

t <- list(A=c(4,1,4),B=c(3,7,9,2))

 > stack(t)
   values ind
1      4   A
2      1   A
3      4   A
4      3   B
5      7   B
6      9   B
7      2   B

If you needed the internal factor of ind that is possible as well

 > as.numeric(stack(t)$ind)
[1] 1 1 1 2 2 2 2

so
data.frame(t=stack(t)$values, levels=as.numeric(stack(t)$ind))

--  
David Winsemius



On Nov 18, 2008, at 10:15 PM, Blanchette, Marco wrote:
> I am pretty sure that I came across a function that creates a vector  
> of levels from a list but I just can't remember.
>
> Basically, I have something like
>
>> t <- list(A=c(4,1,4),B=c(3,7,9,2))
>> t
> $A
> [1] 4 1 4
>
> $B
> [1] 3 7 9 2
>
> And I would like to get something like the following:
> t levels
> 4 1
> 1 1
> 4 1
> 3 2
> 7 2
> 9 2
> 2 2
>
> I tried unlist without success. I also do remember that there is a  
> corresponding function that create a list of t's according to the  
> level from the matrix a draw but no luck to remember it.
>
> Thanks
>
> --
> Marco Blanchette, Ph.D.
> Assistant Investigator
> Stowers Institute for Medical Research
> 1000 East 50th St.
>
> Kansas City, MO 64110
>
> Tel: 816-926-4071
> Cell: 816-726-8419
> Fax: 816-926-2018
>
> ______________________________________________
> 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.