Re: Fast List-Selection
- To: mathgroup at smc.vnet.net
- Subject: [mg19922] Re: [mg19880] Fast List-Selection
- From: Carl Woll <carlw at u.washington.edu>
- Date: Tue, 21 Sep 1999 02:22:53 -0400
- Organization: Physics Department, U of Washington
- References: <199909192247.SAA12942@smc.vnet.net.>
- Sender: owner-wri-mathgroup at wolfram.com
Hi Hans,
Here is one idea:
rep[ls_]:=Position[Partition[ls,7,1],{x_ ..}]
For a 10000 element random list of integers (0,1,2), it took less than a
second. It'll be interesting to see the other solutions.
Carl Woll
Physics Dept
U of Washington
Hans Havermann wrote:
> I have a list 's' composed of a large number of (small) integers. I wish to
> search this list for instances of 7 consecutive, identical elements.
>
> My approach is:
>
> Do[If[Count[t = Take[s, {i, i + 6}], t[[1]]] == 7,
> Print[i]], {i, 1, Length[s] - 6}]
>
> Can anyone think of a *faster* way of doing this?
- References:
- Fast List-Selection
- From: Hans Havermann <haver@total.net>
- Fast List-Selection