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Re: Re: Select Maximum Value

  • To: mathgroup at smc.vnet.net
  • Subject: [mg107990] Re: [mg107948] Re: Select Maximum Value
  • From: Leonid Shifrin <lshifr at gmail.com>
  • Date: Thu, 4 Mar 2010 05:31:34 -0500 (EST)
  • References: <201003020836.DAA03985@smc.vnet.net> <hmj274$eeo$1@smc.vnet.net>

Hi,

You can not use Max as easily as before for your new formulation.

Assuming this is your array:

In[18]:= a = {{{1, 2}, {2, 1}, {3, 4}}, {{1, 5}, {2, 1}, {3, 2}}}


Out[18]= {{{1, 2}, {2, 1}, {3, 4}}, {{1, 5}, {2, 1}, {3, 2}}}

Here are a couple of ways:

In[19]:= Module[{max},
 Fold[If[#1[[2]] < #2[[2]], max = #2, max] &, max = First@#,
    Rest@#] & /@ a]

Out[19]= {{3, 4}, {1, 5}}

In[20]:= Extract[#,
   First@Position[#, {_, Max[#[[All, 2]]]}, 1, 1]] & /@ a

Out[20]= {{3, 4}, {1, 5}}

Regards,
Leonid


On Wed, Mar 3, 2010 at 1:54 PM, graser <graser at gmail.com> wrote:

> On Mar 2, 8:01 am, Patrick Scheibe <psche... at trm.uni-leipzig.de>
> wrote:
> > Hi,
> >
> > it is simply
> >
> > A = {{2, 4, 1, 3, 2, 2}, {4, 7, 9, 1, 2, 4}};
> >
> > Max /@ A
> >
> > and your code is not working at all.
> >
> > Cheers
> > Patrick
> >
> > Am Mar 2, 2010 um 9:36 AM schrieb graser:
> >
> >
> >
> > > Hi
> >
> > > I want to pick up the maximum value of each list  in the Array
> >
> > > A={{2, 4, 1, 3, 2, 2}, {4,7,9,1,2,4}}
> >
> > > I can do it in two steps..
> >
> > > B=Table[Sort[A[[i]], #1>#2&], {i, 1, Length[A]}];
> >
> > > C=Table[B[i], {i, 1, Length[B]}];
> >
> > > But is there any way I can do it in just one step with Select function
> > > or any thing else?
> >
> > > Thanks
>
> Thanks for all of your comments..
>
> Here I have more question for you..
>
> If Array has
>
> A={{1,2},{2,1},{3,4}},{{1,5},{2,1},{3,2}}..
>
> Then If I want to pick up the list which has maximum value in second
> column, So my result should be {{3,4},{1,5}}, can I still use the Max?
>
> It just give the maximum value in first column like {4,5}
>
> Or I have to use the  multiple steps like
>
> B = Table[Sort[A[[i]], #1[[2]] > #2[[2]] &], {i, 1, Length[A]}];
> CD = Table[B[[i, 1]], {i, 1, Length[B]}];
>
>


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