Warning: matrix by vector division
R is working exactly as documented. If you look at how the matrix is stored (column-wise) and then what you are dividing by, you will see that it is doing what you asked (when recycling values):
as.vector(a)
[1] 0 1 1 1 1 1
as.vector(a)/c(2,3)
[1] 0.0000000 0.3333333 0.5000000 0.3333333 0.5000000 0.3333333
On Fri, Mar 7, 2008 at 5:32 PM, Alexey Shipunov <dactylorhiza at gmail.com> wrote:
Dear list, I just made a very simple mistake, but it was hard to spot. And I think that I should warn other people, because it is probably so simple to make... === R code === # Let us create a matrix: (a <- cbind(c(0,1,1), rep(1,3))) # [,1] [,2] # [1,] 0 1 # [2,] 1 1 # [3,] 1 1 # That is a MISTAKE: a/colSums(a) # [,1] [,2] # [1,] 0.0000000 0.3333333 # [2,] 0.3333333 0.5000000 # [3,] 0.5000000 0.3333333 # I just wonder if some R warning should be issued here? # That is what I actually needed (column-wise frequencies): t(t(a)/colSums(a)) # [,1] [,2] # [1,] 0.0 0.3333333 # [2,] 0.5 0.3333333 # [3,] 0.5 0.3333333 === end of R code === With best wishes and regards, Alexey Shipunov
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