Re: Select only certain sublists matching criteria
- To: mathgroup at smc.vnet.net
- Subject: [mg110999] Re: Select only certain sublists matching criteria
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Fri, 16 Jul 2010 05:18:08 -0400 (EDT)
- References: <i1mc7n$8u2$1@smc.vnet.net>
Chris Poole wrote:
> I have a list like this:
> {{0, -4, 2.283}, {0.5, -4, 2.282}, {1, -4, 2.280}, {1.5, -4,
> 2.276}, {2, -4, 2.271}, {2.5, -4, 2.264}, {3, -4, 2.255}, {3.5, -4,
> 2.242}}
>
> I want to look at each list of 3 numbers, and keep only the lists where the third item in each list fits some criteria.
>
> I can do something like this:
> Select[{2, 15, 1, 16, 17}, Abs[3 - #] < 3 &]
>
> But it only works for flat lists.
>
> For example, I want only the lists where the third item is around 2.25 +- 0.001. Something like that.
>
> I can work out how to get Select to operate on the 3rd item of each sublist, but not how to then keep that entire list.
>
> If anyone has any ideas, they are much appreciated.
>
You may use (list is your List)
Select[list,Abs[#[[3]]-2.25]<0.01&]
Out={{3, -4, 2.255}, {3.5, -4, 2.242}}
--
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de