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MathGroup Archive 2004

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Re: Programing operations with lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg50865] Re: Programing operations with lists
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sat, 25 Sep 2004 01:55:03 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <cj0n6t$ld2$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

list1 = {{0.71, 7378}, {1.6, 768}, {2, 2269}, {2.05, 0}, {2.35, 0},
{2.4, 
        2608}, {2.6, 193}, {2.8, 4187}, {2.85, 204}, {2.95, 134}, {3.2, 
        776}, {3.25, 24}, {3.6, 6209}, {3.65, 0}, {3.7, 2809}, {3.95, 
        1923}, {4, 2627}, {4.1, 25}, {4.15, 1}, {4.2, 0}, {4.25, -15},
{4.35, 
        1863}, {4.4, 1797}, {4.45, 7533}, {4.5, 0}, {4.55, 53}, {4.7, 
        12045}, {4.9, 7304}, {4.95, 34}};

list2 = {0.71, 3.2, 4, 4.5, 5};


index = Function[{what},
    Module[{i = 0},
      Catch[
        If[# <= what, i++, Throw[i]] & /@ list2
        ]
      ]
    ]

ll1 = {#[[1]], #[[2]]*f[#[[1]]]} & /@ list1;

Plus @@@ Map[#[[2, 2]] &, 
    Split[{index[First[#]] , #} & /@ Sort[ll1, First[#1] < First[#2] &], 
      First[#1] == First[#2] &], {2}]


???

Regards
  Jens

Guillermo Sanchez wrote:
> 
> Dear group,
> 
> I have two lists with this pattern
> 
> list1={{a1 , b1}, ..., {ai , bi}, ...};
> 
> list2={c1, ..., c(j-1),  cj, ...};
> 
> and a function f[x] (ie: f[x_] = 0.2 x);
> 
> 
> I would like grouping and sum the product bi f[ai] where
> C(j-1)<ai< cj
> 
> 
> I show it with an example:
> 
> list1 = {{0.71, 7378}, {1.6, 768}, {2, 2269}, {2.05, 0}, {2.35, 0},
> {2.4, 2608}, {2.6, 193}, {2.8, 4187}, {2.85, 204}, {2.95, 134},
> {3.2,776}, {3.25, 24}, {3.6, 6209}, {3.65, 0}, {3.7, 2809}, {3.95, 1923},
> {4,2627}, {4.1, 25}, {4.15, 1}, {4.2, 0}, {4.25, -15}, {4.35, 1863},
> {4.4, 1797}, {4.45, 7533}, {4.5, 0}, {4.55, 53}, {4.7, 12045}, {4.9, 7304},
> {4.95, 34}};
> 
> 
> list2 = {0.71, 3.2, 4, 4.5, 5}
> 
> 
> The solution should be:
> 
> {{7378 f[0.71] + .. +134 f[2.95]}, ... , {53 f[4.55]+...+34 f[4.95]}}
> 
> Thanks
> 
> Guillermo


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