[R] How to take the lower triangular part from a full matrix
Romain Francois
romain.francois at dbmail.com
Thu Jun 17 08:43:35 CEST 2010
Le 17/06/10 06:44, ZZY ZYBOYS a écrit :
>
> Dear all:
>
> I have a question regarding on how to take the lower triangular part from a
> full matrix.
> for example
> 1 2 3 1 0 0
> 3 4 5 to 3 4 0
> 7 8 9 7 8 9
>
> Thanks,
> Joey
Please take at least the time to send a reproducible example on how you
make you data, i.e:
> x <- matrix( 1:9, nr = 3, byrow = T )
See ?lower.tri
> x[ upper.tri(x) ] <- 0
Or see ?row and ?col
> x[ row(x) < col(x) ] <- 0
Also note that ??triangular finds lower.tri
Romain
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Romain Francois
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