[R] Extracting part of an array

[Achim Zeileis]

Poizot Emmanuel wrote:
> 
> Hi,
> I've got a trivial question ,but as a newby, I'm stuk.
> I've got an array of dim 160,4. I want to extract the values of the first
> column based on a condition of values in the second column and affect the
> result to a variable.

If I understand you correctly you want something like this:

R> dummy <- matrix(rnorm(160*4), ncol = 4)
R> dim(dummy)
[1] 160   4
R> result <- dummy[(dummy[,2] > 2), 1]
R> result
[1] 1.1762235 0.3720527

Hope that helps
Z


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