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.
>