Re: DeleteCases : several at once, conditions

*To*: mathgroup at smc.vnet.net*Subject*: [mg49380] Re: [mg49369] DeleteCases : several at once, conditions*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sat, 17 Jul 2004 06:38:43 -0400 (EDT)*References*: <200407161006.GAA24904@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 16 Jul 2004, at 19:06, camerzone wrote: > > Suppose you have a list of lists, something like > {{1, 6, 7}, {3, 6, 9}, {1, 2, 11}, {3, 5, 9}, {2, 5, 6}, {2, 9, 11}, { > 2, 10, 11}, {3, 7, 9}, {5, 8, 11}, {3, 7, 9}, {7, 8, 9}, {2, 5, 12}, > {2, 6, > 10}, {2, 10, 11}, {1, 6, 9}, {6, 10, 12}, {3, 6, 12}, {2, 5, 12}, > {3, 8, > 9}, {1, 2, 7}} > and you want to delete cases matching several different patterns, say > {1,_,_} and {9,_,_} > What's the most efficient way? > > Also, can you use conditions with DeleteCases? Say, I want to delete > all cases containing even numbers? > > tks O.K., let ls={{1,6,7},{3,6,9},{1,2,11},{3,5,9},{2,5,6},{2,9,11},{2,10,11},{3,7,9}, { 5,8,11},{3,7,9},{7,8,9},{2,5,12},{2,6,10},{2,10,11},{1,6,9},{6,10,12},{ 3,6,12},{2,5,12},{3,8,9},{1,2,7}}; here we delete all sublists which begin either with 1 or with 2: DeleteCases[ls,{1,__}|{2,__}] {{3, 6, 9}, {3, 5, 9}, {3, 7, 9}, {5, 8, 11}, {3, 7, 9}, {7, 8, 9}, {6, 10, 12}, {3, 6, 12}, {3, 8, 9}} And here we delete all sublists which either begin with 1 or with 2 followed by even integers: DeleteCases[ls,{1,__}|{2,__?EvenQ}] {{3, 6, 9}, {3, 5, 9}, {2, 5, 6}, {2, 9, 11}, {2, 10, 11}, {3, 7, 9}, {5, 8, 11}, {3, 7, 9}, {7, 8, 9}, {2, 5, 12}, {2, 10, 11}, {6, 10, 12}, {3, 6, 12}, {2, 5, 12}, {3, 8, 9}} Andrzej Kozlowski Chiba, Japan http://www.mimuw.edu.pl/~akoz/

**References**:**DeleteCases : several at once, conditions***From:*camerzone@yahoo.com (camerzone)