Re: combinations of n objects 2 at a time
- To: mathgroup at smc.vnet.net
- Subject: [mg15178] Re: combinations of n objects 2 at a time
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Fri, 18 Dec 1998 23:20:22 -0500
- References: <75cvud$3u8@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Albert,
Join@@Table[{i, j}, {i, 6}, {j, 1, i - 1}]
{{2, 1}, {3, 1}, {3, 2}, {4, 1}, {4, 2}, {4, 3}, {5, 1}, {5, 2}, {5, 3},
{5, 4}, {6, 1}, {6, 2}, {6, 3}, {6, 4}, {6, 5}}
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
Albert Maydeu-Olivares wrote in message <75cvud$3u8 at smc.vnet.net>...
Hello,
In order to generate all combinations of n objects 2 at a time I load
the `DiscreteMath` add-on.
<<DiscreteMath`Combinatorica`
l[n_]:=rt[Ksubsets[Reverse[Table[i,{i,n}]],2]]
So that with n=objects I get
l[6]
{{2,1},{3,1},...,{6,4},{6,5}}
Any suggestions on how to do this without loading the add-on?
--
Albert Maydeu-Olivares Tel. +34 3 4021079 ext. 3099 Faculty of
Psychology Fax. +34 3 4021362 University of Barcelona E-Mail:
amaydeu at tinet.fut.es Passeig de la Vall d'Hebron, 171. 08035 -
Barcelona (Spain)