Re: DeleteCases

*To*: mathgroup at smc.vnet.net*Subject*: [mg98166] Re: DeleteCases*From*: Raffy <raffy at mac.com>*Date*: Wed, 1 Apr 2009 05:55:53 -0500 (EST)*References*: <gqsn69$3qp$1@smc.vnet.net>

On Mar 31, 2:19 am, Filippo Miatto <sottosupr... at gmail.com> wrote: > Dear all, > Given this example list: > > {{0, 0, 1, 1}, {0, 0, 2, 2}, {0, 0, 3, 3}, {1, 1, 0, 0}, {1, 1, 2, 2}, = > {1, 1, 3, 3}, {2, 2, 0, 0}, {2, 2, 1, 1}, {2, 2, 3, 3}, {3, 3, 0, 0}, > {3, 3, 1, 1}, {3, 3, 2, 2}} > > I need the elements {a,a,b,b} and {b,b,a,a} to be the same, i.e. i > want to delete one of the two occurrences from the list. (or all but > one if the condition is more complicated, say {a,b,c,d} and {b,a,c,d} > or {a,b,c,d} and {a,b,d,c}) > How can i do that? Can i use DeleteCases? if so, what conditional > should I use to compare different elements in the list? > I tried without success for all the night.. (it's 6.15AM now!) > Thank you, > > Filippo sameQ[_,_] = False; sameQ[{x_, x_, y_, y_}, {y_, y_, x_, x_}] = True; m = {{0, 0, 1, 1}, {0, 0, 2, 2}, {0, 0, 3, 3}, {1, 1, 0, 0}, {1, 1, 2, 2}, {1, 1, 3, 3}, {2, 2, 0, 0}, {2, 2, 1, 1}, {2, 2, 3, 3}, {3, 3, 0, 0}, {3, 3, 1, 1}, {3, 3, 2, 2}}; DeleteDuplicates[m, sameQ] {{0, 0, 1, 1}, {0, 0, 2, 2}, {0, 0, 3, 3}, {1, 1, 2, 2}, {1, 1, 3, 3}, {2, 2, 3, 3}}