[R] Converting a Matrix to a Vector

[Berwin A Turlach]

G'day Ken,

On Wed, 25 Mar 2009 00:13:48 -0700 (PDT)
Ken-JP <kfmfe04 at gmail.com> wrote:

> 
> Say I have:
> 
> > set.seed( 1 )
> > m <- matrix( runif(5^2), nrow=5, dimnames =
> > list( c("A","B","C","D","E"), c("O","P","Q","R","S") ) )
> > m
>           O          P         Q         R         S
> A 0.2655087 0.89838968 0.2059746 0.4976992 0.9347052
> B 0.3721239 0.94467527 0.1765568 0.7176185 0.2121425
> C 0.5728534 0.66079779 0.6870228 0.9919061 0.6516738
> D 0.9082078 0.62911404 0.3841037 0.3800352 0.1255551
> E 0.2016819 0.06178627 0.7698414 0.7774452 0.2672207
> 
> -------------------------------------------------------------------------------------------
> 
> I want to create a vector v from matrix m that looks like this:
> 
> A.O 0.2655087
> B.O 0.3721239
> 
> v <- as.vector( m ) almost gives me what I want, but then I need to
> take combinations of colnames( m ) and rownames( m ) to get my labels
> and hope they match up in order: if not, manipulate the order.  This
> approach feels kludgy...
> 
> Is this the right approach or is there a better way?

R> tt <- reshape(data.frame(m), direction="long", varying=list(1:5), ids=rownames(m), times=colnames(m))
R> ind <- names(tt) %in% c("time", "id")
R> uu <- tt[,!ind]
R> names(uu) <- rownames(tt)
R> uu
       A.O        B.O        C.O        D.O        E.O        A.P        B.P 
0.26550866 0.37212390 0.57285336 0.90820779 0.20168193 0.89838968 0.94467527 
       C.P        D.P        E.P        A.Q        B.Q        C.Q        D.Q 
0.66079779 0.62911404 0.06178627 0.20597457 0.17655675 0.68702285 0.38410372 
       E.Q        A.R        B.R        C.R        D.R        E.R        A.S 
0.76984142 0.49769924 0.71761851 0.99190609 0.38003518 0.77744522 0.93470523 
       B.S        C.S        D.S        E.S 
0.21214252 0.65167377 0.12555510 0.26722067 

HTH.

Cheers,

	Berwin

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Berwin A Turlach                            Tel.: +65 6516 4416 (secr)
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