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MathGroup Archive 2004

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RE: DeleteCases : several at once, conditions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49375] RE: [mg49369] DeleteCases : several at once, conditions
  • From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
  • Date: Sat, 17 Jul 2004 06:38:38 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

>-----Original Message-----
>From: camerzone [mailto:camerzone at yahoo.com]
To: mathgroup at smc.vnet.net
>Sent: Friday, July 16, 2004 12:07 PM
>To: mathgroup at smc.vnet.net
>Subject: [mg49375] [mg49369] DeleteCases : several at once, conditions
>
>
>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
>
>

Read (at Help [Master Index] > Patterns) or try, e.g.:

DeleteCases[lis, {1 | 2, _, _}]

DeleteCases[lis, {x_, _, _} /; x < 3]

DeleteCases[lis, {x_?EvenQ, _, _}]


Let's talk about efficiency later.

-- hw


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