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Re: Finding Clusters

• To: mathgroup at smc.vnet.net
• Subject: [mg117185] Re: Finding Clusters
• From: Yves Klett <yves.klett at googlemail.com>
• Date: Thu, 10 Mar 2011 16:04:02 -0500 (EST)
• References: <il7q9m$dti$1@smc.vnet.net>

Hi,

using Part[] is probably faster for large lists:

tst = {{x -> 9.95043, y -> 0.201587}, {x -> -0.0507389,
    y -> 0.39451}, {x -> -0.0502288 + 0.192544 I,
    y -> 0.199992 - 2.42154*10^-6 I}, {x -> -0.0502288 - 0.192544 I,
    y -> 0.199992 + 2.42154*10^-6 I}, {x -> -0.0507405,
    y -> 0.394519}, {x -> -0.0502287 + 0.192544 I,
    y -> 0.2}, {x -> -0.0502287 - 0.192544 I,
    y -> 0.2}, {x -> -0.0507405, y -> 0.00548135}};
tst[[All, All, 2]] == ({x, y} /. tst)
tst[[All, All, 2]]

The All and Span (est. V6) operators are incredibly useful, have a look
at them.

Regards,
Yves

Am 09.03.2011 13:03, schrieb Martin VavpotiÄ?:
> Hello everyone.
> 
> I have a large array of numbers (1000 =D72). I wish to find clusters in
> that mesh of numbers but the FindClusters method is giving me a hard
> time. I think it's because of those non-numeric leftovers from NSolve
> (x -> and y ->).
> 
> {{x -> 9.95043, y -> 0.201587}, {x -> -0.0507389,
>   y -> 0.39451}, {x -> -0.0502288 + 0.192544 I,
>   y -> 0.199992 - 2.42154*10^-6 I}, {x -> -0.0502288 - 0.192544 I,
>   y -> 0.199992 + 2.42154*10^-6 I}, <<992>>, {x -> -0.0507405,
>   y -> 0.394519}, {x -> -0.0502287 + 0.192544 I,
>   y -> 0.2}, {x -> -0.0502287 - 0.192544 I,
>   y -> 0.2}, {x -> -0.0507405, y -> 0.00548135}}
> 
> I know that if you write something like %[[1,2,2]] you get only the
> numbers but I have a whole array here. How do I get the whole array to
> lose those y -> ?
> 
> Help anyone?
> 

• Follow-Ups:
  • Re: Finding Clusters
    • From: Oliver Ruebenkoenig <ruebenko@wolfram.com>