[R] extract half a matrix
John Fox
jfox at mcmaster.ca
Thu May 22 17:39:51 CEST 2003
Dear Tord,
At 04:55 PM 5/22/2003 +0200, Tord Snall wrote:
>I'm new to matrix operations in R. I couln't find a solution to the
>following problem among earlier help mails or in An introd to R, I guess
>because the question is really basic.
>
>I want to extract all above the diagonal, i.e. from
>
> 1 2 3 4
>1 0 26 49 49
>2 26 0 44 40
>3 49 44 0 21
>4 49 40 21 0
>
>I want
>
>26
>49
>44
>49
>40
>21
>
If you want the result as a one-column matrix,
as.matrix(mat[upper.tri(mat)]) will do the trick.
John
-----------------------------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
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