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Re: Pattern to match a list of non-negative integers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg108955] Re: Pattern to match a list of non-negative integers
  • From: Raffy <adraffy at gmail.com>
  • Date: Thu, 8 Apr 2010 08:01:22 -0400 (EDT)
  • References: <hphbnd$lj5$1@smc.vnet.net> <hphq6g$1i9$1@smc.vnet.net>

On Apr 7, 4:27 am, dh <d... at metrohm.com> wrote:
> On 07.04.2010 09:20, Leo Alekseyev wrote:> This seems like a very basic pattern-matching question, but somehow
> > the answer eludes me at the moment.  I want to match a list of
> > non-negative integers.  Something like MatchQ[{1,2},{(x_Integer /; x
> >> = 0)..}] doesn't work -- do named patterns simply not play well with
> > Repeated[]?..
>
> > After starting to write this message, the following pattern, occurred to me:
> > MatchQ[{2, 3}, x : {_Integer ..} /; ! MemberQ[x, y_ /; Negative[y]]]
> > -- this works, but seems needlessly complex -- so I'll send the
> > message on, in hopes that there is a cleaner way of writing the
> > pattern.
>
> Hi Leo,
> if you repeat something like x_ .., you repeat the x, that is all the
> elements must be the same. Therefore, do not name the pattern. The
> following will work:
> MatchQ[{1, 2}, {_ ?NonNegative ..}]
>
> cheers, Daniel
>
> --
>
> Daniel Huber
> Metrohm Ltd.
> Oberdorfstr. 68
> CH-9100 Herisau
> Tel. +41 71 353 8585, Fax +41 71 353 8907
> E-Mail:<mailto:d... at metrohm.com>
> Internet:<http://www.metrohm.com>

MatchQ[ {1,2}, {_Integer?NonNegative..} ]

MatchQ[ {1,2}, {x__Integer /; NonNegative@Min[x]} ]


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