Loops and memory
On Tue, 6 May 2003, R A F wrote:
I'm afraid that I don't have your new book with Venables handy. So would it be fair to assume that there's no real need to avoid loops these days?
No, but the issues are different from those in 1996. It is a lot less common to have to avoid loops, simply because memory can often be squandered. But vectorizing calculations still pays off, sometimes handsomely: there is an example in that book of going from several hours to one second (and it's a real example).
From: Prof Brian Ripley <ripley at stats.ox.ac.uk> To: R A F <raf1729 at hotmail.com> CC: r-help at stat.math.ethz.ch Subject: Re: [R] Loops and memory Date: Tue, 6 May 2003 20:03:08 +0100 (BST)
That was written in 1996, when rich people had 64Mb of RAM and teaching labs often had 4 or 8Mb (and R would not run much of the code in the book and crashed quite often). Take a look at `S Programming' for a less ancient view.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595