extract half a matrix
A <- array(1:12, dim=c(3,4))
> A[col(A)>row(A)] [1] 4 7 8 10 11 12 This is described in Modern Applied Statistics with S (p. 43 of the 3rd edition; I'm pretty sure I've seen it in the 4th edition, but I don't have that handy just now.) hth. spencer graves
Tord Snall wrote:
Dear all,
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
Thanks in advance!
Sincerely,
Tord
-----------------------------------------------------------------------
Tord Sn?ll
Avd. f v?xtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
Villav?gen 14
SE-752 36 Uppsala, Sweden
Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
E-mail: Tord.Snall at ebc.uu.se
Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!
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