From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-03-28T06:11:27+09:00
Subject: Re: Help to get value from abject inside an array

On Sat, Mar 27, 2010 at 10:01 PM, Nicolas 2b <ndebonfils@gmail.com> wrote:
> Hi,
>
> My problem use RoR object but is ruby oriented so I post here.
> I got an array with lot of objects (type 'Product') like this (only 4
> here) :
>
> [#<Product id: 295147, company_id: 1>, #<Product id: 303667, company_id:
> 2>, #<Product id: 279561, company_id: 9>, #<Product id: 289477,
> company_id: 4>]
>
> What I want to do is iterate on the array and for each company_id, know
> how much products have the same company_id.
> I get the company_id like this : products.collect(&company_id).uniq
>
> but after I don't know how to get an array like this : [1 => 22, 2 =>
> 15, 3 => 9]

I assume you want to get a hash that relates the companyId with the
number of products of that company:

irb(main):016:0> Product = Struct.new :companyId, :productId
=> Product
irb(main):017:0> a = [Product.new(1, 10), Product.new(1,11),
Product.new(2,20), Product.new(3,30)]
=> [#<struct Product companyId=1, productId=10>, #<struct Product companyId=1, p
roductId=11>, #<struct Product companyId=2, productId=20>, #<struct Product comp
anyId=3, productId=30>]
irb(main):018:0> h = Hash.new(0)
=> {}
irb(main):020:0> a.each {|p| h[p[:companyId]] += 1}
=> [#<struct Product companyId=1, productId=10>, #<struct Product companyId=1, p
roductId=11>, #<struct Product companyId=2, productId=20>, #<struct Product comp
anyId=3, productId=30>]
irb(main):022:0> h
=> {1=>2, 2=>1, 3=>1}

Jesus.