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MathGroup Archive 2006

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Re: List Comparison

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67158] Re: [mg67141] List Comparison
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 11 Jun 2006 02:17:16 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

list1={{1,aa,565},{1,bb,566},{1,cc,546},
      {2,dd,56},{2,ff,56},{2,ss,5}};
list2={{1,aa,34},{1,bb,66},{1,cc,5443},
      {2,dd,76},{2,ff,87},{2,mm,87}};

pairs=Thread[{list1,list2}];

result1=If[Take[#[[1]],2]===Take[#[[2]],2],
          Append[#[[1]],Last[#[[2]]]]]&/@
      pairs/.Null:>Sequence[]

{{1, aa, 565, 34}, {1, bb, 566, 66}, {1, cc, 546, 5443}, {2, dd, 56, 76}, {2, ff, 56, 87}}

result2=If[Not[Take[#[[1]],2]===Take[#[[2]],2]],
          #[[1]]]&/@pairs/.Null:>Sequence[]

{{2, ss, 5}}

result3=If[Not[Take[#[[1]],2]===Take[#[[2]],2]],
          #[[2]]]&/@pairs/.Null:>Sequence[]

{{2, mm, 87}}

In version 5.1 or later you can use Pick for result 2 and 3

result2=Pick[list1, Not[Take[#[[1]],2]===
            Take[#[[2]],2]]&/@pairs]

{{2, ss, 5}}

result3=Pick[list2, Not[Take[#[[1]],2]===
            Take[#[[2]],2]]&/@pairs]

{{2, mm, 87}}


Bob Hanlon

---- LectorZ <lectorz at mail.ru> wrote: 
> Dear experts,
> 
> I want to compare two lists containing sublists and make out of them 3
> result lists.
> The comparison applies to the first two elements of the sublists.
> 
> list1 = {{1, aa, 565}, {1, bb, 566}, {
>   1, cc, 546}, {2, dd, 56}, {2, ff, 56}, {2, ss, 5}}
> list2 = {{1, aa,
>   34}, {1, bb, 66}, {1, cc, 5443}, {2, dd, 76}, {2, ff, 87}, {2, mm,
> 87}}
> 
> Result ONE should be:
> 
> If the FIRST element AND the SECOND elements of the sublists are equal,
> then prepend the THIRD elements from list2.
> 
> result1={{1, aa, 565, 34}, {1, bb, 566, 66}, {
>   1, cc, 546, 5443}, {2, dd, 56, 76}, {2, ff, 56, 87}}
> 
> Result TWO should be:
> the FIRST element OR the SECOND elements of the sublists are NOT equal,
> then display the difference from the list1 perspective
> 
> result2={{2, ss, 5}}
> 
> Result THREE should be:
> the FIRST element OR the SECOND elements of the sublists are NOT equal,
> then display the difference from the list2 perspective
> result3={{2, mm, 87}}
> 
> Thanks for your help
> 
> LZ
> 

--

Bob Hanlon
hanlonr at cox.net



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