From: Jean-Denis Muys <jdmuys@...>
Date: 2009-02-06T23:58:43+09:00
Subject: Re: Question - looking for library to use for query like code?

Quoting Mmcolli00 Mom <mmc_collins@yahoo.com>:

> Can this be done with Ruby? (this may be a shot in the dark)
>
> Say you have a text file with a lot of data and you want to group all of
> your data by a specific value. Is there a way to code something in ruby
> similar to a query that you would create using sql. Can this even be
> done using Ruby? And if so, is there a library that you can refer me to?
> If not, do you know any alternative ways? Thanks, MC
>
> example of text:
>
> auto, model
> car, honda
> truck, chevy
> car, nissan
> truck, toyota
> truck, ford
>
>
> how i'd like it to look:
>
> car, honda, nissan,
> truck, chevy, toyota, ford
> --
> Posted via http://www.ruby-forum.com/.
>
>

Of course this is possible, and rather easy to write. Here are bits I would use:

cars = hash.new

file = File.open("textfile.txt")
file.each {
  | line |
  wordarray = line.split(/,\s*/)

  cars[wordarray[0]] << wordarray[1]
}
file.close

file = File.open("outfile.txt", "w")
file << "cars, "
cars["cars"].each { |car| file << car << ", " }
file << "\n"
cars.["truck"].each { |car| file << car << ", " }
file << "\n"
file.close

This is not a complete, nor a general solution, but this should give you an
idea.

Jean-Denis