Re: List difference using patterns and substitutions.
- To: mathgroup at smc.vnet.net
- Subject: [mg71335] Re: List difference using patterns and substitutions.
- From: dh <dh at metrohm.ch>
- Date: Wed, 15 Nov 2006 06:43:40 -0500 (EST)
- Organization: hispeed.ch
- References: <ejc53g$6qf$1@smc.vnet.net>
Hi Nacho, simply drop the first element from your list and subtract from it the list with the last element removed: Drop[list, 1] - Drop[list, -1] or another possibility: Rest[list]-Most[list] Daniel Nacho wrote: > Hello. > > I'm trying to figure how can I build a difference list from another > using only patterns and rule substitutions. > > The idea is to get from a list, another, one element shorter, where > each value is the substraction of two consecutive elements in the > original list, that is, from {1,2,3,5,5} get {1,1,2,0}. > > I've been thinking about it for a while, and I know several methods > using a more traditional programming style (with For, for example), but > I have no idea if it is possible to make it simple and fast with rule > substitutions. > > Any idea? > > Thanks in advance. >