From: Alex Young <alex@...>
Date: 2007-02-16T02:35:41+09:00
Subject: Re: Iterating through 2 fields for one hash, or array.

Peter Bailey wrote:
> Hello,
> I'm using Jamey Cribbs' KirbyBase as a database. The beauty of it is, of
> course, that it's all pure Ruby. . . .
> 
> I need to iterate through a table with multiple fields. I've shown here
> a very rudimentary example of the data that I'm working with.
> 
>    Cost Center    Page Count
>      TMUS00           64
>      ER0000           32
>      DER000          128
>      TMUS00           32
>      DER000           64
>      ER0000           10
> 
> I want to iterate through the table and create a hash, or an array, that
> includes a single entry for each cost center and the total number of
> pages counted for that cost center. So, I'd like to end up with
> something like this below. I'm thinking I need a hash because the cost
> center would be the key, with the page count being its value.
> 
>    Cost Center     Page Count
>      TMUS00            96
>      ER0000            42
>      DER000           192
I don't know the syntax for getting the data out of KirbyBase, but the 
trick I usually use for this sort of thing is a hash with a default 
value.  Something like:

@cost_centers = Hash.new(0)
def add_to_cost_centers(center_key, amount)
	@cost_centers[center_key] += amount
end

Hope this helps,
-- 
Alex