[R] How to force a vector to be column or row vector?

[Liaw, Andy]

From: Gabor Grothendieck
> 
> Try this:
> 
> 
> rbind(c(x))
> cbind(c(x))
> t(c(x))

The c() is not needed above.

Also, this might be a better way of computing a quadratic form:

> x <- 1:3
> m <- matrix(sample(1:9), 3, 3)
> crossprod(crossprod(m, x), x) 
     [,1]
[1,]  202
> t(x) %*% m %*% x   # Just checking...
     [,1]
[1,]  202

In R, it usually makes little difference whether a vector is row-vector or
column-vector.

Andy

 
> On 2/2/06, Michael <comtech.usa at gmail.com> wrote:
> > Hi all,
> >
> > I tended to use rbind, or cbind to force a vector be be 
> deemed as a column
> > or row vector. This is very important if I want to do 
> things like u' * A *
> > u, where u' is a row vector and u is a column vector, 
> regardless of what
> > originall format  the "u" is... I want to recast it to 
> column vector or row
> > vector...  How can I do that?
> >
> > ----------------------------------------------------
> >
> >
> > b_hat=solve(t(X) %*% X) %*% t(X) %*% Y;
> >
> > attr(b_hat, "dim")
> > [1] 4 1
> >
> > rbind(b_hat)
> >       [,1]
> >  -4.814763
> > V -5.804245
> >  -5.122668
> >  -4.308326
> >
> >        [[alternative HTML version deleted]]
> >
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