R help - Jun 2011 - conversion of matrix into list

Dear all,

 

I have a matrix X which consists of 2 columns. I would like to convert this
matrix into a list where every entry of the list consists of a single row of
the matrix.

Does anyone have a suggestions how to manage this?

 

Thank you for your efforts in advance!

 

Best,

 

Martin

 


	[[alternative HTML version deleted]]

Hi
 
> Dear all,
> 
> 
> 
> I have a matrix X which consists of 2 columns. I would like to convert 
this
> matrix into a list where every entry of the list consists of a single 
row of
> the matrix.
e.g.

split(mat, 1:nrow(mat))

Regards
Petr
> 
> Does anyone have a suggestions how to manage this?
> 
> 
> 
> Thank you for your efforts in advance!
> 
> 
> 
> Best,
> 
> 
> 
> Martin
> 
> 
> 
> 
>    [[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.

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Martin Spindler wrote:
> I have a matrix X which consists of 2 columns. I would like to convert this
> matrix into a list where every entry of the list consists of a single row
of
> the matrix.
Here's another way besides split():

# returns a list of the matrix m's rows (rowcol=1) or columns
mat2lst <- function(m,rowcol=1) {
   if (rowcol == 1) m <- t(m)
   dm <- as.data.frame(m)
   as.list(dm)
}

This seems to be faster than the split() approach for columns, but
slower for rows.  Apparently the transpose operation makes the
difference.  (You could try investigating via Rprof().)

Norm Matloff