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MathGroup Archive 2004

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Re: DeleteCases : several at once, conditions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49402] Re: DeleteCases : several at once, conditions
  • From: "Eckhard Hennig" <aidev at n-o-s-p-a-m.kaninkolo.de>
  • Date: Sat, 17 Jul 2004 06:39:48 -0400 (EDT)
  • References: <cd8b1n$olb$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"camerzone" <camerzone at yahoo.com> schrieb im Newsbeitrag
news:cd8b1n$olb$1 at smc.vnet.net...
> 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?

Use a pattern with Alternatives (|):

DeleteCases[list, {1 | 9, _, _}]

> Also, can you use conditions with DeleteCases?  Say, I want to delete
> all cases containing even numbers?

You can use a conditional rule (/;) to achieve this:

DeleteCases[list, x_ /; Or @@ EvenQ[x]]

Best regards,

  Eckhard

-- 
Dr.-Ing. Eckhard Hennig
www.kaninkolo.de/ai
aidev \at kaninkolo \dot de



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