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MathGroup Archive 2005

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Re: arrange lists side by side

  • To: mathgroup at smc.vnet.net
  • Subject: [mg56575] Re: arrange lists side by side
  • From: Peter Pein <petsie at arcor.de>
  • Date: Fri, 29 Apr 2005 03:20:48 -0400 (EDT)
  • References: <d4q1qj$oh8$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

marloo3 at mail15.com wrote:
> Hi
> is there a way to spread out a small list over a bigger list recurrently like 
> this:
> a={28, 30, 17};
> b={1, 2, 9, 4, 5, 7, 3, 8};
> to give the output:
> {{1,28},{2,30},{9,17},{4,28},{5,30},{7,17},{3,28},{8,30}};
> the number of items in "b" do not neccesary  multiples of the number of items 
> in "a"
> mark
> 
> okay this is my approach
> 
> a={28,30,17};
> b={1,2,9,4,5,7,3,8};
> aa={};aa=Table[Join[aa,a],{i,Length[b]/Length[a]}]
> 
> Out[]=
> {{28,30,17},{28,30,17}}
> 
> frc=Mod[Length[b],Length[a]];
> gg=Flatten[Join[aa,Part[a,{1,frc}]]];
> Transpose[Join[{b},{gg}]]
> 
> Out[]=
> {{1,28},{2,30},{9,17},{4,28},{5,30},{7,17},{3,28},{8,30}}
> 
> ----------------------------------------------------------------------
> 
> 
There are many ways to do this. Three are:

MapIndexed[{#1,a[[Mod[#2[[1]],Length[a],1]]]}&,b]

Transpose@Prepend[Partition[a,Length[b],1,{1,Length[a]}],b]

Inner[List,b,PadRight[a,Length[b],a],List]

-- 
Peter Pein
Berlin


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