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MathGroup Archive 2007

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Re: Selecting Sub-lists After Split

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77446] Re: [mg77425] Selecting Sub-lists After Split
  • From: János <janos.lobb at yale.edu>
  • Date: Sat, 9 Jun 2007 05:27:42 -0400 (EDT)
  • References: <200706080934.FAA03592@smc.vnet.net>

On Jun 8, 2007, at 5:34 AM, Gregory Lypny wrote:

> Hello everyone,
>
> Suppose I have a list of real number called myList.  I split it into
> sub-lists of positive and negative numbers called myNewList by doing
> this (there may be a more elegant way):
>
> myNewList = Split[myList, #1 #2 > 0 &]
>
> Now, how can I select all of the sub-lists of negative numbers from
> myNewList?
>
> Any tips would be most appreciated.
>
> Regards,
>
> 	Gregory


Here is a newbie approach:

First[Last[Reap[i = 1; While[i <= Length[newlst],
       If[First[newlst[[i]]] < 0, Sow[newlst[[i]]], Null]*
         i++; ]]]]

newlst is your MyNewList.

J=E1nos


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