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Re: Question about Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106576] Re: Question about Mathematica
  • From: Peter Breitfeld <phbrf at t-online.de>
  • Date: Sat, 16 Jan 2010 06:15:36 -0500 (EST)
  • References: <hipld8$7po$1@smc.vnet.net>

"Dominic" wrote:

> Hi.  Can someone help me with the following question:
>
> I have a table of a table of number pairs:
>
> {{{1,2),(3,-1),{2,-4)},{{1,2},{4,-5},{6,-8}},{{2,-1},{-2,-3},{-4,6}}}
>
> How may I find the minimum second element in each sub-table?  For 
> example, the first sub-table is:
>
> {{1,2},{3,-1},{2,-4}}
>
> I would like to then extract the {2,-4} element from this item.  Then 
> the {6,-8} from the second sub-table, then the {-2,-3} element from the 
> last.
>
> Thank you,
> Dominic
>
>

This is a possibility:

ll = {{{1, 2}, {3, -1}, {2, -4}}, {{1,2}, {4, -5}, {6, -8}},
      {{2, -1}, {-2, -3}, {-4, 6}}}

minsecond[l:{{_,_}..}]:=Sort[l,#1[[2]]<#2[[2]]&]

First /@ (minsecond /@ ll)

Out= {{2, -4}, {6, -8}, {-2, -3}}

-- 
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de


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