[R] apply and arrays
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Jul 25 08:58:53 CEST 2005
On Mon, 25 Jul 2005, Uwe Ligges wrote:
> Laura Holt wrote:
>> Hi R!
>> I have a 3 dimensional array, which is 21 x 3 x 3
>> I want to use apply to sum on each 21x3 matrix, which is fine.
>> Is there a way that I can do this in 1 step instead of a loop (3), please?
> Don't know which direction you mean, I guess one of the following:
> apply(x, c(1,2), sum)
> apply(x, 3, sum)
Or use rowSums or colSums for clarity (and speed, irrelevant here).
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
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