[R] Getting multiple matrix-values using a single command

[Claudia Beleites]

use a matrix of n x 2 to index. For details: sec. 5.3 "Index matrices" in the 
introduction.

HTH Claudia

Nils Rüfenacht wrote:
> Dear all!
> 
> I'm trying to get multiple values from a matrix by using a single command.
> 
> Given a matrix A
> 
> A <- matrix(seq(1,9),nrow=3,ncol=3)
> 
> How can I get e.g. the values A[1,2] = 4 and A[3,3] = 9 with a single 
> command and without using any loop? My first idea was to generate a row- 
> and a column vector for the indices, i.e. c(1,3) indicating row number 1 
> (for A[1,2]) and row number 3 (for A[3,3]) and similar for 
> column-indices. Then I've tried to call
> 
> A[c(1,3),c(2,3)]
> 
> but instead of 4 , 9 the result is
> 
> [,1] [,2]
> [1,]    4    7
> [2,]    6    9
> 
> Any suggestions?
> 
> Regards, Nils
> 
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-- 
Claudia Beleites
Dipartimento dei Materiali e delle Risorse Naturali
Università degli Studi di Trieste
Via Alfonso Valerio 6/a
I-34127 Trieste

phone: +39 0 40 5 58-37 68
email: cbeleites at units.it