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Re: Word permutations - frustrated by lists.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg71713] Re: Word permutations - frustrated by lists.
  • From: dh <dh at metrohm.ch>
  • Date: Mon, 27 Nov 2006 04:04:35 -0500 (EST)
  • References: <ekbrks$jga$1@smc.vnet.net>


Hi,

the easy way to get permutations is:

<< DiscreteMath`Combinatorica`

Permutations[{"d", "e", "a", "r"}]

Daniel



wooks wrote:

> Hello. Am relatively new with Mathematica.

> 

> I seem to have a general problem with results that look right but for

> embedded lists. Here is an example of my problem. This is supposed to

> be a algorithm to generate all permutations of a string. T

> 

> Clear[arrangements]

> arrangements[str_String /; StringLength[str] == 1] := {str};

> arrangements[str_String] := (Prepend[arrangements[StringJoin[

>     Rest[#]]]], First[#]) & /@

>        NestList[RotateRight, Characters[str], StringLength[str] - 1];

> arrangements["dear"]

> 

> PS This is not homework. I'm rewriting some examples from another

> programming book as as practice  for Mathematica.

> 



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