A=matrix(0,nr=3,nc=4)
A[sample(prod(dim(A)),1)]=1
>>>
From: "Barroso, Judit"
To:"r-help@r-project.org"
Date: 10/Nov/2010 11:12a
Subject: [R] Change a value in a matrix randomly
I have a matrix of ceros, for example:
0 0 0 0
0 0 0
Tena koe Judit
If it is really a matrix (and not a data.frame) and you wish to change a
randomly selected zero to a one, then
judit <- matrix(0, nrow=3, ncol=4)
judit[sample(1:length(judit), 1)] <- 1
will do. This uses the fact that a matrix is a vector with a dim attribute.
HTH
Peter A
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