Re: [R] Combinations

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Prof Brian D Ripley (ripley@stats.ox.ac.uk)
Tue, 14 Dec 1999 13:11:00 +0000 (GMT) 




On Tue, 14 Dec 1999, Chuck Cleland wrote:



>   Why not use expand.grid() and subscript away any unwanted rows?



How are you going to work out which ones are unwanted, efficiently? And for


moderately sized problems you will run out of space in expand.grid, as


there are many more k-tuples than combinations. (More than k! times


as many.)



-- 
Brian D. Ripley,                  ripley@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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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