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Re: Delete elements from list..

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116627] Re: Delete elements from list..
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Tue, 22 Feb 2011 04:42:31 -0500 (EST)

On 2/21/11 at 7:30 PM, Maarten.VanDerBurgt at kla-tencor.com (Maarten
van der Burgt) wrote:

>I have a list like:

>mylist = {1, 2, 3, 4, 5, 6, 4, 5, 7, 8, 9}

>I want to delete any element which is not strictly larger than the
>previous element, until my new list has only increasing values.

>This means in mylist above I want to delete the 4 and the 5 at
>position 7 and 8.

>Any elegant and fast way for doing this?

Here is one way that should be reasonably fast for a large list

In[29]:= Rest@
  Flatten@Fold[If[Last[#1] < #2, {#1, #2}, #1] &, {0}, mylist]

Out[29]= {1,2,3,4,5,6,7,8,9}

as for elegance, I'll leave that for you to decide.



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