harder parts of list
- To: mathgroup at smc.vnet.net
- Subject: [mg15570] harder parts of list
- From: Arnold Knopfmacher <arnoldk at gauss.cam.wits.ac.za>
- Date: Tue, 26 Jan 1999 13:44:48 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
This seems to be a harder list parts problem. Given a list like
lst={{4,2,3,1},{3,1,5},{2,4,3}}
I wish to select the elements in each sublist that are smaller than the
first
entry in that sublist.
So for the above lst the output should be {{2,3,1},{1},{}}. How can I
do this with Select or Cases?
Using pattern matching this works
rule1={a_,b___,c_,d___}:>{a,b,d} /;c>a
(# //. rule1)& /@ lst
{{4,2,3,1},{3,1},{2}}
Rest /@ %
{{2,3,1},{1},{}}
Thanks
Arnold Knopfmacher
Wiws University
South Africa