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

*To*: mathgroup at smc.vnet.net*Subject*: [mg108932] Re: Pattern to match a list of non-negative integers*From*: Leo Alekseyev <dnquark at gmail.com>*Date*: Wed, 7 Apr 2010 07:25:30 -0400 (EDT)*References*: <hphbnd$lj5$1@smc.vnet.net> <4BBC5963.3010105@metrohm.com>

I don't know why I didn't think about _?. How silly of me! Since I want to also enforce the Integer property, what I need is MatchQ[{1, 2}, {_?(NonNegative[#] && Head[#] === Integer &) ..}] I am guessing this is the cleanest way to do it... On Wed, Apr 7, 2010 at 6:07 AM, dh <dh 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:dh at metrohm.com> > Internet:<http://www.metrohm.com> > >