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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


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