[R] Problem at subsetting matrix by using dimnames
Agustin Lobo
aloboaleu at gmail.com
Wed Sep 2 11:57:46 CEST 2009
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
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