       Re: Combinations

• To: mathgroup at smc.vnet.net
• Subject: [mg49696] Re: [mg49672] Combinations
• From: Sseziwa Mukasa <mukasa at jeol.com>
• Date: Thu, 29 Jul 2004 07:43:05 -0400 (EDT)
• References: <200407271100.HAA11164@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```On Jul 27, 2004, at 7:00 AM, Gregory Lypny wrote:

> Hello everyone,
>
> Does Mathematica have a built-in function that will generate a simple
> list all possible combinations of a list of strings?  For example,
> {a,b,c}, where the elements are strings, should give 3x3=27 triplets of
> "aaa", "aba", etc.
>
> I tried
>
> In:=Outer[{a,b,c},{a,b,c},{a,b,c}]
>
> but I get
>
> {{{a, b, c}[a, a], {a, b, c}[a, b], {
>      a, b, c}[a, c]}, {{a, b, c}[b, a], {a, b, c}[b, b], {a, b,
>        c}[b, c]}, {{a, b, c}[c, a], {a, b, c}[c, b], {a, b, c}[c, c]}}
>
> which is going to be difficult to match with my data using BinCounts
> and the like.

You want to use

Flatten[Outer[List, {a, b, c}, {a, b, c}, {a, b, c}], 2]

The first argument to outer is a function that's applied to the
combinations.  The rest of the arguments are the lists to combine.  The
Flatten reduces the rank of the tensor that's returned, see the help
browser for details.

Regards,

Ssezi

```

• References:
• Combinations
• From: Gregory Lypny <gregory.lypny@videotron.ca>
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