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A better way to decimate a file??

• To: mathgroup at smc.vnet.net
• Subject: [mg21350] A better way to decimate a file??
• From: rob-piovere at swbell.net (Rob Peterson)
• Date: Tue, 28 Dec 1999 00:49:35 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

I start with a list y that I need to decimate (sp?).  I've looked thru
the book and the only list function I can find to dump list elements
is the Drop[] function.  But, the best I can do is get rid of half of
the elements at a time.  I want to decimate this list by 16, ie I want
to dump 15 of every 16 entries.  So, I dump half of them four times.
This seems to work but I figure the pros hanging in this group will
know a much more elegant way to do this.  I did this:

(* start with y as the list  and ly = Length[y]  *)

y2 = Drop[y, {1, ly, 2}]; ly2 = Length[y2]

y4 = Drop[y2, {1, ly2, 2}]; ly4 = Length[y4]

and so on

So how should it really be done?  I'd like to be able to decimate by
non-binary numbers too.

Thanks, Rob

• Follow-Ups:
  • Re: A better way to decimate a file??
    • From: Andrew Watson <abwatson@mail.arc.nasa.gov>