[R] subsetting a list of matrices

[Marco Geraci]

Hi. Have you tried 'help.search('list')' ?
See ?lapply

> lapply(z, function(s) s[2:3,,drop=F])
[[1]]
     [,1] [,2]
[1,]    2    5
[2,]    3    6

[[2]]
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]   19   22   25   28   31   34
[2,]   20   23   26   29   32   35


Marco Geraci

--- Federico Calboli <f.calboli at imperial.ac.uk> wrote:

> Hi All,
> 
> I have a list of matrices:
> 
> > x
>      [,1] [,2]
> [1,]    1    4
> [2,]    2    5
> [3,]    3    6
> > y
>      [,1] [,2] [,3] [,4] [,5] [,6]
> [1,]   18   21   24   27   30   33
> [2,]   19   22   25   28   31   34
> [3,]   20   23   26   29   32   35
> > z =list(x,y)
> 
> I want to create a second list that is has a subset
> each matrix in the
> list subsetting so I get the 2nd and 3rd row of each
> (and all columns).
> 
> How could I do that (apart from looping)?
> 
> Regards,
> 
> Federico Calboli
> 
> -- 
> Federico C. F. Calboli
> Department of Epidemiology and Public Health
> Imperial College, St Mary's Campus
> Norfolk Place, London W2 1PG
> 
> Tel  +44 (0)20 7594 1602     Fax (+44) 020 7594 3193
> 
> f.calboli [.a.t] imperial.ac.uk
> f.calboli [.a.t] gmail.com
> 
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