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

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Fri 03 Feb 2006 - 01:27:15 EST


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@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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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Feb 03 01:35:40 2006

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