R help - Sep 2009 - Problem at subsetting matrix by using dimnames

Given:

 > mitest <- matrix(1:16,ncol=4)
 > dimnames(mitest)[[1]] <-
c("a","b","c","d")
 > dimnames(mitest)[[2]] <-
c("a","b","c","d")
 > mitest
  a b  c  d
a 1 5  9 13
b 2 6 10 14
c 3 7 11 15
d 4 8 12 16

I can do:
 > mitest[cbind(c(1,2,3),c(2,3,2))]
[1]  5 10  7

but using the names does not work:
 >
mitest[cbind(c("a","b","c"),c("b","c","b"))]
[1] NA NA NA NA NA NA

despite the fact that
 > mitest["a","b"]
[1] 5

works fine.

How can I do the equivalent of
 > mitest[cbind(c(1,2,3),c(2,3,2))]

using row and column names?

Thanks

Agus


-- 
Dr. Agustin Lobo
Institut de Ciencies de la Terra "Jaume Almera" (CSIC)
LLuis Sole Sabaris s/n
08028 Barcelona
Spain
Tel. 34 934095410
Fax. 34 934110012
email: Agustin.Lobo at ija.csic.es
http://www.ija.csic.es/gt/obster

Try this:

mapply(function(x, y)mitest[x, y], c("a", "b",
"c"), c("b", "c", "b"))

or

diag(`[`(mitest, i = c("a", "b", "c"), j =
c("b", "c", "b")))



On Wed, Sep 2, 2009 at 6:57 AM, Agustin Lobo <aloboaleu@gmail.com> wrote:
> Given:
>
> > mitest <- matrix(1:16,ncol=4)
> > dimnames(mitest)[[1]] <-
c("a","b","c","d")
> > dimnames(mitest)[[2]] <-
c("a","b","c","d")
> > mitest
>  a b  c  d
> a 1 5  9 13
> b 2 6 10 14
> c 3 7 11 15
> d 4 8 12 16
>
> I can do:
> > mitest[cbind(c(1,2,3),c(2,3,2))]
> [1]  5 10  7
>
> but using the names does not work:
> >
mitest[cbind(c("a","b","c"),c("b","c","b"))]
> [1] NA NA NA NA NA NA
>
> despite the fact that
> > mitest["a","b"]
> [1] 5
>
> works fine.
>
> How can I do the equivalent of
> > mitest[cbind(c(1,2,3),c(2,3,2))]
>
> using row and column names?
>
> Thanks
>
> Agus
>
>
> --
> Dr. Agustin Lobo
> Institut de Ciencies de la Terra "Jaume Almera" (CSIC)
> LLuis Sole Sabaris s/n
> 08028 Barcelona
> Spain
> Tel. 34 934095410
> Fax. 34 934110012
> email: Agustin.Lobo@ija.csic.es
> http://www.ija.csic.es/gt/obster
>
> ______________________________________________
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]