[R] Coerce rectangular matrix to symmetrical square matrix

[Dimitris Rizopoulos]

one way is the following:

mat <- matrix(1:12, 3, 4, TRUE)
dimnames(mat) <- list(c("A", "E", "F"), LETTERS[1:4])

cnams <- colnames(mat)
rnams <- rownames(mat)
unq.nams <- unique(c(cnams, rnams))
out <- matrix(0, length(unq.nams), length(unq.nams),
     dimnames = list(unq.nams, unq.nams))
p1 <- paste(cnams[col(mat)], rnams[row(mat)], sep = "\\")
p2 <- paste(unq.nams[col(out)], unq.nams[row(out)], sep = "\\")
out[match(p1, p2)] <- mat
out <- out + t(out)
diag(out) <- diag(out)/2
out


I hope it helps.

Best,
Dimitris


Nathan S. Watson-Haigh wrote:
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> I have a rectangular matrix of size 920 by 85. I'd like to coerce it into a
> square matrix such that all row/col names are present in the new matrix and the
> additional values are zero.
> 
> As an example:
> 
>    A  B  C  D
> A  1  2  3  4
> E  5  6  7  8
> F  9 10 11 12
> 
> Would be coerced to:
>    A  B  C  D  E  F
> A  1  2  3  4  5  9
> B  2  0  0  0  6 10
> C  3  0  0  0  7 11
> D  4  0  0  0  8 12
> E  5  6  7  8  0  0
> F  9 10 11 12  0  0
> 
> Any thoughts on how to achieve this?
> 
> Cheers,
> Nathan
> 
> 
> - --
> - --------------------------------------------------------
> Dr. Nathan S. Watson-Haigh
> OCE Post Doctoral Fellow
> CSIRO Livestock Industries
> Queensland Bioscience Precinct
> St Lucia, QLD 4067
> Australia
> 
> Tel: +61 (0)7 3214 2922
> Fax: +61 (0)7 3214 2900
> Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
> - --------------------------------------------------------
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-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
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