Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Selecting Sub-lists After Split

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77455] Re: Selecting Sub-lists After Split
  • From: DrMajorBob <drmajorbob at bigfoot.com>
  • Date: Sat, 9 Jun 2007 05:32:21 -0400 (EDT)

walk == Rest@NestList[# + Random[] - 1/2 &, 0, 1000];
signedRuns == Split[walk, #1 #2 > 0 &];
Length /@ signedRuns
negativeRuns == Select[signedRuns, First[#] < 0 &];
Length /@ negativeRuns

{12, 11, 2, 22, 1, 207, 2, 3, 78, 1, 202, 38, 66, 355}

{12, 2, 1, 2, 78, 202, 66}

I didn't let negativeRuns display, but I think that's what you wanted.

Bobby

On Fri, 08 Jun 2007 04:34:49 -0500, Gregory Lypny 
<gregory.lypny at videotron.ca> 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
>
>



--
DrMajorBob at bigfoot.com


  • Prev by Date: Re: Re: v6: still no multiple undo?
  • Next by Date: Re: Selecting Sub-lists After Split
  • Previous by thread: Re: Selecting Sub-lists After Split
  • Next by thread: Re: Selecting Sub-lists After Split