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Re: Making a lists with conditions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg85745] Re: [mg85676] Making a lists with conditions
  • From: Sseziwa Mukasa <mukasa at jeol.com>
  • Date: Wed, 20 Feb 2008 07:07:13 -0500 (EST)
  • References: <200802190653.BAA27541@smc.vnet.net>

On Feb 19, 2008, at 1:53 AM, Guillermo Sanchez wrote:

> Dear group
>
> I have two list (list1:{a1, ...ai,  aj, ..., an}, list2:{{ai,
> bi}, ..., {aj, bj}}.
>
> I wish to obtain a new list (list3} where be included all members of
> list1 and list2. If elements ak is not included in list2 then write
> {ak, 0}.
>
> Here is an example:
>
> list1 = {3.8,  3.85, 3.9,  3.95,  4., 4.05,  4.1};
> list2 = {{3.85, 120}, { 4.0 , 111}, {4.1, 314}};
>
> ff[list1_, list2_] := =BFlist1, list2?
>
>
> Here is the ouput that I wist to obtain
>
> Out:={{3.8, 0} , {3.85`, 120}, {3.9`, 0}, {3.95, 0}, {4.`, 111},
> {4.05`, 0}, {4.1`, 314}}
>
> I have a method but it is two complicate. I am sure that some members
> of the group will find a elegant solution

I'm not sure about elegance but the following works when list1 is at  
least as long as list2 and every ai in list2 has a corresponding  
entry in list1

combine[list1_, list2_] :=
  Module[{result = list1},
   result[[Flatten[Position[list1, #] & /@ list2[[All, 1]]]]] = list2;
   If[AtomQ[#], {#, 0}, #] & /@ result]

Regards,

Ssezi


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