[Rd] Dropping dimnames doesn't matter (anymore)?

Bjørn-Helge Mevik bhs2 at mevik.net
Fri May 12 14:48:59 CEST 2006

In the "old days", one way of speeding up matrix calculations was to
drop the dimnames of the matrices prior to the calculations, i.e.,
dimnames(X) <- NULL.  I distinctly remember that this could have a
great impact at least in Splus 3.x (under UNIX/Linux).

I just did a small, informal test of this with a couple of functions I
use to fit plsr models, in R 2.3.0 (Linux).  It didn't seem to have
any effect at all (the functions actually ran a tiny bit slower,
probably due to the "dimnames(X) <- NULL" command).

Is the "general rule-of-thumb" with current R versions that the
overhead of keeping the dimnames through calculations is negligible?

Bjørn-Helge Mevik

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