Rui
Thanks. This works great. Below, I get the 2nd, 4th, and 6th rows/columns:
> (a<-matrix(1:36,6,6))
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 1 7 13 19 25 31
[2,] 2 8 14 20 26 32
[3,] 3 9 15 21 27 33
[4,] 4 10 16 22 28 34
[5,] 5 11 17 23 29 35
[6,] 6 12 18 24 30 36
> (j<-matrix(c(0,1,0,1,0,1)))
[,1]
[1,] 0
[2,] 1
[3,] 0
[4,] 1
[5,] 0
[6,] 1
> ((a[as.logical(j), as.logical(j)]))
[,1] [,2] [,3]
[1,] 8 20 32
[2,] 10 22 34
[3,] 12 24 36
Steven Yen
At 02:49 PM 10/26/2014, Rui Barradas wrote:
Sorry, that should be
t(a[as.logical(j), as.logical(j)])
Rui Barradas
Em 26-10-2014 18:45, Rui Barradas escreveu:
Hello,
Try the following.
a[as.logical(j), as.logical(j)]
# or
b <- a[as.logical(j), ]
t(b)[as.logical(j), ]
Hope this helps,
Rui Barradas
Em 26-10-2014 18:35, Steven Yen escreveu:
Dear
I am interested in selecting rows and columns of a matrix with a
criterion defined by a binary indicator vector. Let matrix a be
> a<-matrix(1:16, 4,4,byrow=T)
> a
[,1] [,2] [,3] [,4]
[1,] 1 2 3 4
[2,] 5 6 7 8
[3,] 9 10 11 12
[4,] 13 14 15 16
Elsewhere in Gauss, I select the first and third rows and columns of a
by defining a column vector j = [1,0,1,0]. Then, select the rows of a
using j, and then selecting the rows of the transpose of the resulting
matrix using j again. I get the 2 x 2 matrix as desired. Is there a way
to do this in R? below are my Gauss commands. Thank you.
---
j
1
0
1
0
a=selif(a,j); a
1 2 3 4
9 10 11 12
a=selif(a',j); a
1 9
3 11
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______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
