From: Jens Wille <jens.wille@...>
Date: 2008-04-27T02:50:48+09:00
Subject: Re: Howto get array.agrep (NOT array.grep)

Phil Rhoades [2008-04-26 19:13]:
> This might work but it would be more difficult without regexs -
> the current application does a system call to agrep but of course
> it is very slow for large numbers of calls.  A typical call is
> something like:
> 
>   agrep -2 "Smith\|J.*12345" list1.txt list2.txt list3.txt
> 
> This allows two differences on a minimum amount of information 
> consisting of last name, first initial and zip code.  If I use
> the Enumerable version, I would have to use the whole, delimited,
> name & address string and increase the differences/distance
> number?
i think something like that could work in your case (requires the
Text gem):

  File.open('list1.txt').select { |line|
    # extract name and zip code from line
    line =~ /\A(.*?\|.).*\b(\d{5})\b/  # adjust appropriately!

    # name may have two errors, zip only one -- or whatever...
    Text::Levenshtein.distance($1, 'Smith|J') <= 2 &&
Text::Levenshtein.distance($2, '12345') <= 1
  }

> Did you just do that hack now?
that's right. but i just read a bit on agrep's algorithm and it
might be fun to implement it in ruby (though a bit slow, probably).
as an alternative, it might be even worth writing ruby bindings to
agrep. who knows, if time permits... ;-)

> - how do I get/install it? (Fedora 8).
well, i don't think that particular implementation suits your needs
and is obviously easily adapted (after all, it's just a select with
an appropriate block utilizing Text::Levenshtein.distance). but you
can get ruby-nuggets from rubyforge (gem install ruby-nuggets), or,
if the new version hasn't found its way onto the mirrors yet, from
our own gem server at http://prometheus.khi.uni-koeln.de/rubygems/.

cheers
jens