# Re: [R] Equivalent of Mathematica's Apply

From: Juan Pablo Romero Méndez <jpablo.romero_at_gmail.com>
Date: Tue, 24 Jun 2008 18:24:35 -0500

Thanks all!

JP

On Tue, Jun 24, 2008 at 3:30 PM, Franz Mueter <fmueter_at_alaska.net> wrote:
> Try
>
>> apply(ind, 1, function(i) x[i:i])
>
> which returns a matrix if all sequences are the same length, a list
> otherwise
>
> -----Original Message-----
> From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org] On
> Behalf Of Juan Pablo Romero Méndez
> Sent: Tuesday, June 24, 2008 11:51 AM
> To: r-help_at_stat.math.ethz.ch
> Subject: [R] Equivalent of Mathematica's Apply
>
> Hello,
>
> Is there some equivalent function in R of Mathematica's "Apply"
>
> i.e.
>
> Apply[ f, g[a,b]] ==> f[a,b]
>
>
> In concret, I have a matrix of indexes:
>
>> ind = cbind(1:5, 1:5+5)
>
>> ind
>
> [,1] [,2]
> [1,] 1 6
> [2,] 2 7
> [3,] 3 8
> [4,] 4 9
> [5,] 5 10
>
>
> and I'd like to extract sequences 1:6, 2:7, 3:8, ..., 5:10 from a vector x.
>
> What would be the most compact way of achieving this?
>
> I've tried
>
> sapply(1:5, function(i) x[ind[i,1] : ind[i,2]])
>
>
> Although
>
> sapply(1:5, function(i) x[seq(ind[i,])])
>
> would be better (if it worked).
>
> Regards,
>
> Juan Pablo
>
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