Re: Extract Elements from a List?

*To*: mathgroup at smc.vnet.net*Subject*: [mg28979] Re: Extract Elements from a List?*From*: "Allan Hayes" <hay at haystack.demon.co.uk>*Date*: Thu, 24 May 2001 04:06:56 -0400 (EDT)*References*: <9efk6g$1d8@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

"Robert Schuerhuber" <robert.schuerhuber at gmx.at> wrote in message news:9efk6g$1d8 at smc.vnet.net... > i need to extract elements from a list, starting th element number x and > than taking every yth element, eg: > > with > > list={a,b,c,d,e,f,g,h,i,j} > start=3; > step=2: > > i'd like to get the list > > {c,e,g,i}. > Robert, ?Take gives .... Take[list, {m, n, s}] gives elements m through n in steps of s. ... So with, lst={a,b,c,d,e,f,g,h,i,j}; start=3; step=2; we get Take[lst, {start, -1,2}] {c,e,g,i} For negative integers the position n is the -n th, counting left with the last position given by -1. --------------------- 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