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Re: identical rows in tables

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97601] Re: identical rows in tables
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Mon, 16 Mar 2009 06:28:19 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <gpl5qr$oss$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,
> I have a table of values
> 
> e.g.{{1, 2, 3, 4, 5, 6, 7, 8}, {1, 4, 6, 2, 8, 3, 7, 5}, {1, 4, 2, 6, 3,
>   8, 5, 7}, {1, 3, 2, 5, 4, 7, 6, 8}, {1, 3, 5, 2, 7, 4, 8, 6}, {1, 2,
>    4, 3, 6, 5, 8, 7}, {1, 2, 3, 4, 5, 6, 7, 8}}
> 
> and want to check if any rows are identical (so there are none in the above=
>  - I can remove last or first row which are supposed to be the same).

tab = {{1, 2, 3, 4, 5, 6, 7, 8}, {1, 4, 6, 2, 8, 3, 7, 5}, {1, 4, 2,
    6, 3, 8, 5, 7}, {1, 3, 2, 5, 4, 7, 6, 8}, {1, 3, 5, 2, 7, 4, 8,
    6}, {1, 2, 4, 3, 6, 5, 8, 7}, {1, 2, 3, 4, 5, 6, 7, 8}} ;

{Length[tab],
  Length[tab /. {a___, b_, c___, b_, d___} :> {a, b, c, d}]}

gives
{7,6}

> 
> But in the following {{1, 2, 3, 4, 5, 6, 7, 8}, {1, 4, 6, 2, 8, 3, 7, 5}, {=
> 1, 4, 2, 6, 3,
>   8, 5, 7}, {1, 3, 2, 5, 4, 7, 6, 8}, {1, 3, 5, 2, 7, 4, 8, 6}, {1, 8,
>    7, 6, 5, 4, 3, 2}, {1, 8, 6, 7, 4, 5, 2, 3}, {1, 3, 2, 5, 4, 7, 6,
>   8}, {1, 3, 5, 2, 7, 4, 8, 6},....}
> 
>  there is a pair {1, 3, 2, 5, 4, 7, 6,
>   8}, {1, 3, 5, 2, 7, 4, 8, 6} which are the same.
> 
> In an ideal world when I print out (in say TableForm)  the repeated rows ca=
> n be printed in red (or some specified colour)

So looks the ideal world ??

Grid[tab, ItemStyle -> {Automatic,
    MapIndexed[If[# > 1, #2[[1]] -> Red, #2[[1]] -> Blue] & ,
     Count[tab, #] & /@ tab]}]

> 
> These rows are permutations if that makes any difference. The tables can be=
>  of any size (but always permutations of n numbers)
> 
> as a subsidiary question is there an easy way to convert the tables into nu=
> mbers (or strings) eg
> 
> {12345678,14628375,14263857 etc}
> 

StringJoin @@@ Map[ToString, tab, {2}]

> Alternatively is there an easy way to perform permutations on strings of ch=
> aracters?
> 

PermuteString[str_] :=
  With[{lst = Characters[str]},
   StringJoin @@ RandomSample[lst, Length[lst]]]

and

PermuteString["I can't read the manual!"]

work as expected

Regards
   Jens


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