From: George Lunsford <george.lunsford@...>
Date: 2005-11-22T01:53:54+09:00
Subject: Re: Regular Expressions and Ruby

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I am matching +i, sorry for leaving that out. I copied the expression from
the regex coach, which has that handy checkbox. Thanks for the optimized
info for the future. Ruby/Regex coach doesn't seem to like the optimized
version though either...

 On 11/21/05, Christian Neukirchen <chneukirchen@gmail.com> wrote:
>
> George Lunsford <george.lunsford@gmail.com> writes:
>
> > Hi, I'm new to the list and I hope this is the right place to ask the
> > question, but I recently started learning ruby and I was writing a shor=
t
> > little program to test if a word was made up of symbols from the
> periodic
> > table. I figured I'd use ruby's built-in regex support, so I ended up
> > writing a regex that looks something like this:
> > (element1|element2|element3...|elementx)+
> > Basically it's just got all 115 or so of the elements in there, and it'=
s
> > testing for one or more, right? Unfortunately this doesn't seem to work
> > properly as a (nonsense) word like "presenti" should be periodic
> according
> > to my list of elements, [p][re][se][n][ti]. Now, I can duplicate this
> > behavior with the regex coach oddly enough. The problem seems to be tha=
t
> it
> > parses [p][re][s] instead of [se]. I'm wondering if anyone can explain
> this
> > behavior to me, as I'm new to both regexps and ruby and the only regex
> > experience I've had previous to this is in some theory classes. Thanks.
> The
> > full expression is below.
> >
> >
> (He|Li|Be|C|O|Ne|Na|Mg|Al|Si|S|Cl|Ar|Ca|Sc|Ti|Cr|Mn|Fe|Co|Ni|Cu|Zn|Ga|Ge|=
As|Se|Br|Kr|Rb|Sr|Zr|Nb|Mo|Tc|Ru|Rh|Pd|Ag|Cd|In|Sn|Sb|Te|Xe|Cs|Ba|Hf|Ta|Re|=
Os|Ir|Pt|Au|Hg|Tl|Pb|Bi|Po|At|Rn|Fr|Ra|Rf|Db|Sg|Bh|Hs|Mt|Uun|Uuu|Uub|Uuq|Uu=
h|Uuo|Ds|La|Ce|Pr|Nd|Pm|Sm|Eu|Gd|Tb|Dy|Ho|Er|Tm|Yb|Lu|Ac|Th|Pa|Np|Pu|Am|Cm|=
Bk|Cf|Es|Fm|Md|No|Lr|H|B|N|F|P|V|Y|I|W|Uaal)+
>
> Are you matching case insensitive (/i)?
>
> By the way, an optimized version of that regexp is
>
>
> /(A[cglmr-u]|B[aehikr]|C[adeflmorsu]|D[bsy]|E[rsu]|F[emr]|G[ade]|H[efgos]=
|I[nr]|Kr|L[airu]|M[dgnot]|N[abdeiop]|Os|P[abdmortu]|R[abefhnu]|S[bcegimnr]=
|T[abcehilm]|U(?:aal|u[bhnoqu])|Xe|Yb|Z[nr]|[BCFHINOPSVWY])+/
>
> (Thanks to emacs's regexp-opt)
> --
> Christian Neukirchen <chneukirchen@gmail.com> http://chneukirchen.org
>
>

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