From: "Älphä Blüë" <jdezenzio@...>
Date: 2009-07-18T22:24:12+09:00
Subject: Hash of Hash of Arrays Question

Hi all,

I decided to take a deep look into hashes today and how hashes of arrays
are handled.  This is a bit of a grasp for me because most of the
languages I've worked with, arrays are handled in just a few ways.  With
Ruby, it's much better.

So, here are my questions using an example scenario I'm creating from
scratch.

Creating a new Hash:

myhash = Hash.new {|h,k| h[k] = {} }
myhash.class
=> Hash

Creating two Arrays:

mykeyarray = Array.[](1,2,3,4,5)
=> [1, 2, 3, 4, 5]

myvaluearray = Array.[](10,20,30,40,50)
=> [10, 20, 30, 40, 50]

5.times do |i|
  myhash[mykeyarray[i]][:numbers] = myvaluearray[i]
end

myhash.keys
=> [5, 1, 2, 3, 4]

myhash.values
=> [{:numbers=>50}, {:numbers=>10}, {:numbers=>20}, {:numbers=>30},
{:numbers=>40}]

myhash.inspect
=> "{5=>{:numbers=>50}, 1=>{:numbers=>10}, 2=>{:numbers=>20},
3=>{:numbers=>30}, 4=>{:numbers=>40}}"

So, I would believe that this is a hash of hashes of arrays correct?

Secondly, how would I parse information out of this hash?  Creating them
is easy.  Extracting exactly the way I want - not so easy.

Let me give you an example:

I create a constant that stores the symbol I want to use for my table.

MY_TABLE_FIELD = [:numbers]

myhash.each do |key|
  values = {:compiled_on => Date.today.strftime('%Y-%m-%d')}
  MY_TABLE_FIELD.each_with_index do |field, i|
    values[field] = key[i]
  end
  model.create values
end

.. this won't work ..

I want to match the symbol in my hash with the symbol in my constant
(which represents the table field).  I want to update the table field
with the value of the hash (10,20,30,40,50).  They hash key would
represent the id field (1,2,3,4,5).

How can I accomplish this given the information provided?
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