[R] Equivalent of Mathematica's Apply
Franz Mueter
fmueter at alaska.net
Tue Jun 24 22:30:01 CEST 2008
Try
> apply(ind, 1, function(i) x[i[1]:i[2]])
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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