Re: position lists
- To: mathgroup at smc.vnet.net
- Subject: [mg68712] Re: position lists
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Thu, 17 Aug 2006 04:18:18 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <ebujvu$6lu$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
rych wrote:
> have
> In: a = {1, 1, 2, 2, 1, 4}
> want
> {{1, 2, 5}, {3, 4}, {0}, {6}};
>
> more effectively than just
> In: Position[a, #] & /@ Range[4]
> Out: {{{1}, {2}, {5}}, {{3}, {4}}, {}, {{6}}}
>
> Ideas? Known one-liners?
> Thanks
> Igor
>
Hi Igor,
I am not sure whether this might be what you are looking for,
(Flatten[Position[a, #1]] & ) /@ Range[4]
--> {{1, 2, 5}, {3, 4}, {}, {6}}
HTH,
Jean-Marc