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MathGroup Archive 1998

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Re: Select x s.t. y>10

  • To: mathgroup at smc.vnet.net
  • Subject: [mg14019] Re: [mg13957] Select x s.t. y>10
  • From: "Jens-Peer Kuska" <kuska at linmpi.mpg.de>
  • Date: Wed, 16 Sep 1998 14:12:00 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

say Your data are named data than You can just write what you want

First[Select[data,Last[#]>5 &]]

If You don't like to waste time computing all elements larger than 5 
You can write

Catch[Scan[If[Last[#]>5,Throw[#],Null] &,data]]

If You don't like Catch and Throw You can still use pattern matching
with

First[data /. {x_,y_?NumericQ} /; y<=5 :> Sequence[]]

Hope that helps
  Jens

-----Original Message-----
From: Jason Gill <jgill at vbimail.champlain.edu> To:
mathgroup at smc.vnet.net
Subject: [mg14019] [mg13957] Select x s.t. y>10


>I came across what seems like it should be a simple little function, but
>could not come up with a clever way to implement it.  Generally, what I
>am trying to do is take a list of lists of length 2 ie a list of x,y
>coordinates, and Select x values based on some criterion for y.  For
>example I want to select the first x value for which the corresponding
>y is greater than 5.
>I can write a function using Position and Take etc. , but there must be
>a clever,and more efficient way to do this.  Any thoughts... Jason
>
>--
>Jason Gill
>IBM Microelectronics
>Essex Junction, VT 05452
>Phone   (802)769-3350
>Fax     (802)769-1220
>email:  jgill at vbimail.champlain.edu
>           jasongil at us.ibm.com
>
>
>



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