[R] Help creating a symmetric matrix?

[Rui Barradas]

Matt Considine wrote
> 
> Hi,
> I am trying to work with the output of the MINE analysis routine found at
>    http://www.exploredata.net
> 
> Specifically, I am trying to read the results into a matrix (ideally an 
> n x n x 6 matrix, but I'll settle right now for getting one column into 
> a matrix.)
> 
> The problem I have is not knowing how to take what amounts to being one 
> half of a symmetric matrix - excluding the diagonal - and getting it 
> into a matrix.  I have tried using "lower.tri" as found here
>    https://stat.ethz.ch/pipermail/r-help/2008-September/174516.html
> but it appears to only partially fill in the matrix.  My code and an 
> example of the output is below.  Can anyone point me to an example that 
> shows how to create a matrix with this sort of input?
> 
> Thank you in advance,
> Matt
> 
> #v<-newx[,3]
> #or, for the sake of this example
> v<-c(0.33740, 0.26657, 0.23388, 0.23122, 0.21476, 0.20829, 0.20486, 
> 0.19439, 0.19237,
> 0.18633, 0.17298, 0.17174, 0.16822, 0.16480, 0.15027)
> z<-diag(6)
> ind <- lower.tri(z)
> z[ind] <- t(v)[ind]
> 
> z
>          [,1]    [,2] [,3] [,4] [,5] [,6]
> [1,] 1.00000 0.00000    0    0    0    0
> [2,] 0.26657 1.00000    0    0    0    0
> [3,] 0.23388 0.19237    1    0    0    0
> [4,] 0.23122 0.18633   NA    1    0    0
> [5,] 0.21476 0.17298   NA   NA    1    0
> [6,] 0.20829 0.17174   NA   NA   NA    1
> 
> 
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> 
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> 

Hello,

Aren't you complicating?

In the last line of your code, why use 'v[ind]' if 'ind' indexes the matrix,
not the vector?

z<-diag(6)
ind <- lower.tri(z)
z[ind] <- v                        #This works
z

Rui Barradas


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