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Re: Generalizing Complement to handle multiple occurrences

• To: mathgroup at smc.vnet.net
• Subject: [mg112446] Re: Generalizing Complement to handle multiple occurrences
• From: "Niels R. Walet" <niels.walet at manchester.ac.uk>
• Date: Wed, 15 Sep 2010 20:03:29 -0400 (EDT)
• References: <201009150838.EAA21715@smc.vnet.net>

Mark Coleman wrote:
> Greetings,
>
> I'm wondering how one can efficiently generalize the built-in
> Complement function to return multiple occurrences of elements. For
> instance, the current version generates
>
> a={1,2,2,3,4,4,4,4}
> b={3,5,7}
>
> Complement[a,b]={1,2,4}
>
> I'm looking for a way to define
>
> myComplement[a,b]={1,2,2,4,4,4,4}
>
> My current code is very inefficient!
>
> Thanks,
>
> Mark
>
>   
Stupid oneliner:
c = a; Apply[(c = DeleteCases[c, #]) &, b]

-- 
Prof. Niels R. Walet                   Phone:  +44(0)1613063693
School of Physics and Astronomy        Fax:    +44(0)1613064303
The University of Manchester           Mobile: +44(0)7905438934
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email: Niels.Walet at manchester.ac.uk 
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• References:
  • Generalizing Complement to handle multiple occurrences of elements
    • From: Mark Coleman <markspcoleman@gmail.com>