[R] convert a vector to a symmetric matrix with all 0 on the diagonal

Rui Barradas ruipbarradas at sapo.pt
Sun Jan 12 23:27:12 CET 2014


You should address your questions to R-Help, the odds of getting more 
and better answers are greater.

As for your question, the trick is to use function ?lower.tri. (There's 
also an upper.tri) Something like the following.

x <- 1:6

m <- matrix(0, nrow = 4, ncol = 4)
m[lower.tri(m)] <- x
res <- m + t(m)

Hope this helps,

Rui Barradas

Em 12-01-2014 21:21, yolande.tra at gmail.com escreveu:
> Hi Rui,
> You might not remember me but you have been very helpful in the past wit questions related to R. I saw one of your reply about creating a lower triangular matrix from a vector.
> I have a column in a data frame that I want to convert to a symmetric matrix with all 0 on the diagonal.
> Could you help?
> I appreciate.
> Thanks,
> Yolande
> _____________________________________
> Sent from http://r.789695.n4.nabble.com

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