Re: Building List
- To: mathgroup at smc.vnet.net
- Subject: [mg48032] Re: Building List
- From: Mark Fisher <mark at markfisher.net>
- Date: Sat, 8 May 2004 01:23:36 -0400 (EDT)
- References: <c7fhhg$o9u$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
How's this?
modifylist[list_List] :=
Block[{g},
(g @@ list) /. {a_, b__ /; Length[{b}] > 1} :>
Sequence @@ Thread[{a, {b}}] /. g -> List
]
--Mark
Bruce W. Colletti wrote:
> Re Mathematica 5.0.1.0.
>
> I have a list of lists -- e.g., L = { {1,2},{3,4,5,6},{7,8} } -- and
> want to replace element-lists (whose length exceeds 2) with another list
> built from that element. All else is untouched.
>
> For instance, using L above, replace {3,4,5,6} with {3,4}, {3,5}, {3,6}.
> This transforms L to the desired form { {1,2}, {3,4}, {3,5}, {3,6},
> {7,8} }.
>
> Although I can do this using Sow and Reap, am hoping there's an easier
> way using rules (/.). In general, I want to replace those L-elements x
> (that meet a criterion) with foo[x].
>
> Thanks.
>
> Bruce
>