Re: Word permutations - frustrated by lists.

*To*: mathgroup at smc.vnet.net*Subject*: [mg71720] Re: Word permutations - frustrated by lists.*From*: Peter Pein <petsie at dordos.net>*Date*: Mon, 27 Nov 2006 04:04:53 -0500 (EST)*References*: <ekbrks$jga$1@smc.vnet.net>

wooks schrieb: > 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. > What about In[1]:= Apply[StringJoin, Permutations[Characters["dear"]], {1}] Out[1]= {"dear", "dera", "daer", "dare", "drea", "drae", "edar", "edra", "eadr", "eard", "erda", "erad", "ader", "adre", "aedr", "aerd", "arde", "ared", "rdea", "rdae", "reda", "read", "rade", "raed"} ?