Re: [R] Help to make a specific matrix

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Sun 10 Jul 2005 - 11:21:42 EST

On 7/9/05, Jose Claudio Faria <joseclaudio.faria@terra.com.br> wrote:
> Dear R users,
>
> The solution is probably simple but I need someone to point me to it.
> How can I to generate a matrix from a numeric sequence of 1:10 like 'A' or 'B'
> below:
>
> A)
> |--------------------|
> | 1 2 3 4 5 |
> |--------------------|
> | 1 | 0 |
> | 2 | 1 0 |
> | 3 | 2 5 0 |
> | 4 | 3 6 8 0 |
> | 5 | 4 7 9 10 0 |
> |--------------------|
>
> B)
> |--------------------|
> | 1 2 3 4 5 |
> |--------------------|
> | 1 | 0 1 2 3 4 |
> | 2 | 1 0 5 6 7 |
> | 3 | 2 5 0 8 9 |
> | 4 | 3 6 8 0 10 |
> | 5 | 4 7 9 10 0 |
> |--------------------|
>

Try this and see ?lower.tri

A <- matrix(0,5,5)
A[lower.tri(A)] <- 1:10
B <- A + t(A)



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