Re: Obtaining sequences from lists of lists
- To: mathgroup at smc.vnet.net
- Subject: [mg36208] Re: [mg36168] Obtaining sequences from lists of lists
- From: BobHanlon at aol.com
- Date: Tue, 27 Aug 2002 02:07:15 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 8/26/02 6:11:47 AM, rdobrow at carleton.edu writes:
> If I have an n-element list, (say where each element is itself a
> list), such as {{a,b}, {a,b}, {a,b}}
> is there a way to strip off the outermost nesting of the list to
> obtain just a sequence of of these n elements, that is
> {a,b},{a,b},{a,b} so that I can use this for input for some function.
>
> I would like to do something like
> Outer[SomeFunction, Table[{a,b},{N} ]] where I can enter N
> dynamically.
> The problem, of course, is that the output of the Table command is one
> big list
> and Outer is expecting a sequence of N separate lists after
> SomeFunction.
>
Use Sequence
kTuples[n_Integer?Positive,s_List]:=
Flatten[Outer[List,Sequence@@Table[s,{n}]],n-1];
s = {a,b,c,d,e}; n =3;
Length[kTuples[n,s]] == Length[s]^n
True
Bob Hanlon
Chantilly, VA USA