extract positions from matrix
Here's one approach:
A=matrix(1:15,5)
B=matrix(15:29,5)
C=matrix(30:44,5)
do.call(cbind, lapply(c("A","B","C"),function(x) get(x)[c(1,5),1]))
Michael
On Thu, Nov 17, 2011 at 9:44 PM, .Jpg <jporobicg at gmail.com> wrote:
Hi everyone, I tried to solve this problem but I could not find the solution. I have about 105 matrices of equal size in the memory of**R, I need to do is extract from these matrices some known positions and create a new matrix with these columns. Show you an example with only three matrices (but in my case I have hundreds of them). A=matrix(1:15,5) [,1] [,2] [,3] [1,] 1 6 11 [2,] 2 7 12 [3,] 3 8 13 [4,] 4 9 14 [5,] 5 10 15 B=matrix(15:29,5) [,1] [,2] [,3] [1,] 15 20 25 [2,] 16 21 26 [3,] 17 22 27 [4,] 18 23 28 [5,] 19 24 29 C=matrix(30:44,5) [,1] [,2] [,3] [1,] 30 35 40 [2,] 31 36 41 [3,] 32 37 42 [4,] 33 38 43 [5,] 34 39 44 The positions I wish to extract are 1 and 5 of the first row of each matrix (in my case are 25positions) and with this generate a new matrix with the form d= [,1] [,2] [,3] [1,] 1 15 30 [2,] 5 19 34 The ideais to builda loop toextract thisinformation from hundredsmatrices, butI failed todo so. Any helpwould be greatthank you very muchin advance regards .jpg ? ? ? ?[[alternative HTML version deleted]]
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