Subject: Re: chol() dimnames
From: Jonathan Rougier (J.C.Rougier@durham.ac.uk)
Date: Mon 27 Sep 1999 - 22:02:39 EST
On Mon, 27 Sep 1999, Prof Brian Ripley wrote:
> This is a picky comment, but maybe we should try to get this spot on.
> (i) Suppose that the row and column names of x are different? Which should
> one use?
> (ii) I don't think that R has any obvious row names: effectively this is
> a linear transformation to a different and unamed basis for the space.
> I believe all one actually knows is that the colnames of R should be the
> colnames of x, if the row and column names of x match. However, the
> prototype does preserve the names. Should we just preserve the colnames?
I think your qualms would be answered if the attribution of dimnames was
only made in the event that x has matching row and column names. Whether
just the column names should be preserved in this case is a moot point.
But you might imagine a cautious programmer wanting to be sure that the
row names of Q correspond with the row names of some other matrix A in the
calculation t(Q) %*% A. Preserving the row names doesn't do any harm, and
it might just be helpful.
Jonathan Rougier Science Laboratories
Department of Mathematical Sciences South Road
University of Durham Durham DH1 3LE
"[B]egin upon the precept ... that the things we see are to be
weighed in the scale with what we know" (Meredith, 1879, The Egoist)
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