From: WJ <w_a_x_man@...>
Date: 2011-04-18T01:35:26+09:00
Subject: Re: Help on hashing multiple keys and values

Adam Adam wrote:

> I'm trying to create a hash with multiple values per key from a tab
> delimited file. numbers_and_colors.txt example:
> 
> 1    Red
> 2    Blue
> 3    Red
> 2    Green
> 
> What I need is a hash that has key 2 assigned to values Blue and Green.
> Running what I have below just erases the previous key, so puts
> name_hash["2"] would only show Green. Ruby example:
> 
> name_hash = Hash.new
> File.open("numbers_and_colors.txt").each do |file_line|
>   file_line.chomp!
>   line_parts = file_line.split(/\t/)
>   name_hash["#{line_parts[0]}"] = "#{line_parts[1]}"
> 
> I need this in a hash, so is there another way to go about this? Thanks
> in advance to any help, as you can probable tell I only started learning
> Ruby recently.

name_hash = {}
name_hash.default = []
IO.foreach( "data2" ){|line|
  key, val = line.split
  name_hash[ key ] += [val]
}
p name_hash

  ==>

{"1"=>["Red"], "2"=>["Blue", "Green"], "3"=>["Red"]}