Re: Parts of a list
- To: mathgroup at smc.vnet.net
- Subject: [mg15493] Re: Parts of a list
- From: "Donald E. Niman <niman.at.ieee.org>" <Donald at newsguy.com>
- Date: Mon, 18 Jan 1999 04:22:36 -0500
- Organization: Consultant
- References: <77jkve$304@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In a dream I recall that on 13 Jan 1999 21:32:14 -0500, in article
<77jkve$304 at smc.vnet.net>, "Hossein blurted out thus...
>
>I have a list (matrix) that looks like this
>
>x={{1,0},{2.5, .5},{3,0},{0,2}}
>
>Now I want to eliminate those vectors that have zero for the second
>case. That is, I want to get
>
>{{2.5, .5},{0,2}}.
>
>Is there a quick way of doing this?
>I tried to apply Select to this but could not get it to work.
>
>Thanks for your help.
>
>Hossein Kazemi
>UMass
>kazemi at som.umass.edu
>
>
>
The Select function works with anonymous functions. Anonymous functions
have two variations in syntax. Here are some solutions using both:
Given your list,
x={{1,0},{2.5, .5},{3,0},{0,2}};
Select[x,(#[[2]]!=0)&]
and
Select[x,Function[y,y[[2]]!=0]]
both give the desired result.
Donald E. Niman
Peoria Arizona and Rancho Cucamonga California My opinions today do not
necessarily reflect my earlier opinions.