Re: A better way to decimate a file??
- To: mathgroup at smc.vnet.net
- Subject: [mg21353] Re: A better way to decimate a file??
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Wed, 29 Dec 1999 14:15:41 -0500 (EST)
- References: <849j3v$pgm@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Rob, Two suggestions: data = Range[100]; Flatten[Partition[data, 1, 16], 1] {1, 17, 33, 49, 65, 81, 97} data[[Range[1, Length[data], 16]]] {1, 17, 33, 49, 65, 81, 97} Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Rob Peterson" <rob-piovere at swbell.net> wrote in message news:849j3v$pgm at smc.vnet.net... > 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 >