[R] replace() in matrix

[Guido Masarotto]

On Mon, Jul 02, 2001 at 06:51:40PM +0200, Tord Snall wrote:
> How do I replace values of a matrix, for exemple I want the matrix
> 
> 1	24	1	1	1
> 24	1	1	1	1
> 1	1	1	45	104
> 1	1	45	1	92
> 1	1	104	92	1
> 
> to be replaced by 
> 
> 0	24	0	0	0
> 24	0	0	0	0
> 0	0	0	45	104
> 0	0	45	0	92
> 0	0	104	92	0
> 
> Could someone please help me with that?


It is explained in the "An introduction to R" manual (which is included
in the main R distribution) under
"Index vectors: selecting and modifying subsets of a data set"

An example is
> a <- matrix(c(1,24,1,103,56,1,1,1,27),3,3)
> a
     [,1] [,2] [,3]
[1,]    1  103    1
[2,]   24   56    1
[3,]    1    1   27
> a[a<=1] <- 0 
> a
     [,1] [,2] [,3]
[1,]    0  103    0
[2,]   24   56    0
[3,]    0    0   27
> 

guido




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