Re: Select in Math.
- To: mathgroup at smc.vnet.net
- Subject: [mg16576] Re: Select in Math.
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Wed, 17 Mar 1999 23:54:55 -0500
- References: <7clc04$9k0@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 3/8/99 6:43:38 PM, kewjoi at hixnet.co.za writes:
>My question is how can I extract (select) list of lists in increasing
>order?
>For example:
>In[2]:=list={{{1,2,3,4},{1,2,4,3}},{{2,3,1},{5}},{6,7}}
>Out[2]={{{1,2,3,4},{1,2,4,3}},{{2,3,1},{5}},{6,7}}
>
>I 'd like to obtain only the parts in increased order, therefore the
>result should be :
>Out[3]={{1,2,3,4},{5},{6,7}}
>I did try (Cases, Select, and Extract) but definitely not in proper way.
>
One problem is that the lists that you seek seem to be at different levels.
We can tackle this either by specifying the pattern of these lists:
list={{{1,2,3,4},{1,2,4,3}},{{2,3,1},{5}},{6,7}};
Cases[list,{___Integer}? OrderedQ, Infinity ]
{{1,2,3,4},{5},{6,7}}
Or by noting that they are all in fact at level -2 (this is probably the
quicker
way)
Cases[list,_?OrderedQ, {-2} ]
{{1,2,3,4},{5},{6,7}}
Allan
---------------------
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