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MathGroup Archive 2005

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Re: Maximum y-value in a list of xy pairs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg61177] Re: [mg61124] Maximum y-value in a list of xy pairs
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 12 Oct 2005 01:42:03 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

pairs={{0,0.175},{1,0.54},{2,0.27},{3,0.47},{4,0.325},{5,0.527},{6,0.22},{7,
        0.742},{8,0.109},{9,0.3314},{10,0.1481}};

Sort[pairs,#1[[2]]>#2[[2]]&]//First

{7, 0.742}

If you want all occurences whose y value is the max

Select[pairs,#[[2]]==Max[pairs[[All,2]]]&]

{{7, 0.742}}


Bob Hanlon

> 
> From: mike_in_england2000 at yahoo.co.uk
To: mathgroup at smc.vnet.net
> Date: 2005/10/11 Tue AM 03:20:14 EDT
> Subject: [mg61177] [mg61124] Maximum y-value in a list of xy pairs
> 
> Hi
> 
> Is there an easy way of finding the maximum y-value of a list of x-y
> pairs?  For example:
> 
> pairs = {{0, 0.175}, {1, 0.54}, {2, 0.27}, {3, 0.47}, {4, 0.325}, {5,
>       0.527}, {6, 0.22}, {7, 0.742}, {8, 0.109}, {9, 0.3314}, {10,
> 0.1481}}
> 
> Max[pairs] gives 10 which isnt what I want.  At the moment I am doing
> this:
> 
> maxy = 0;
> Do[
>   currentx = pairs[[count]][[1]];
>   currenty = pairs[[count]][[2]];
>   If[currenty > maxy,
>     maxy = currenty;
>     x = currentx;
>     ];
>   , {count, 1, Length[pairs]}
>   ]
> Print[{x, maxy}]
> 
> Which gives the maximum y value along with with its x-value but I
> suspect that there is a much more elegant way.  Any help would be
> appreciated.
> 
> Thanks,
> 
> Mike
> 
> 


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