Re: position lists
- To: mathgroup at smc.vnet.net
- Subject: [mg68897] Re: [mg68688] position lists
- From: János <janos.lobb at yale.edu>
- Date: Tue, 22 Aug 2006 05:20:48 -0400 (EDT)
- References: <200608160736.DAA06180@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On Aug 16, 2006, at 3:36 AM, 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
Not a one-liner, but gives a closer approximation to the desired result:
In[19]:=
Flatten[Last[Reap[i = 1;
lenlst = Length[lst];
While[i <= lenlst,
Sow[Flatten[Position[
lst, i]], i];
i++; ], Range[
Max[lst]]]], 2]
Out[19]=
{{1, 2, 5}, {3, 4}, {}, {6}}
János
---------------------------------------------------------
What is the difference between OS X and Vista ?
Microsoft employees are exited about OS X.
http://daringfireball.net/2006/04/windows_the_new_classic
- References:
- position lists
- From: "rych" <rychphd@gmail.com>
- position lists