Re: Combinations
- To: mathgroup at smc.vnet.net
- Subject: [mg61716] Re: [mg61677] Combinations
- From: Sseziwa Mukasa <mukasa at jeol.com>
- Date: Thu, 27 Oct 2005 05:01:43 -0400 (EDT)
- References: <200510260501.BAA18717@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On Oct 26, 2005, at 1:01 AM, xxxxyz at abv.bg wrote:
> Hi,
>
> Is there any way to generate combinations per turn in a cycle? I mean
> first generate one combination, do something, generate next, do the
> same thing ...
>
> Thanks.
The combinations are called KSubsets in Mathematica, the
Combinatorica package contains the necessary routines. The first
KSubset in lexicographic order is simply Range[k], you can use
NextKSubset to see the others for example:
<<DiscreteMath`Combinatorica`
Block[{subset = Range[3]},Prepend[Table[subset = NextKSubset[Range
[5], subset], {4}], Range[3]]]
will return the first 5 subsets of length 3 of {1,2,3,4,5} in
lexicographic order. There are functions to get the KSubsets in
other orders in Combinatorica, I suggest you read the Help Browser
information or read "Computational Discrete Mathematics:
Combinatorics and Graph Theory with Mathematica" by Steven Skiena and
Sriram Pemmaraju for more information on the package.
Regards,
Ssezi
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- From: "xxxxyz@abv.bg" <xxxxyz@abv.bg>
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