# Help to get value from abject inside an array **URL:** \ **Category:** Ruby\ **Created:** [March 27, 2010, 10:00pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867 "2010-03-27T22:00:54Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![nicolas2b](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/3ab097/32.png) [@nicolas2b](https://www.ruby-forum.com/u/nicolas2b)\ **Post date:** [March 27, 2010, 10:00pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867/1 "2010-03-27T22:00:54Z")
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) : [#\, #\, #\, #\] 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] Thanks for your help * * * Nicolas ---
**Author:** ![nicolas2b](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/3ab097/32.png) [@nicolas2b](https://www.ruby-forum.com/u/nicolas2b)\ **Post date:** [March 27, 2010, 10:04pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867/2 "2010-03-27T22:04:06Z")
Sorry for the errors in the title, if someone could correct them :S ---
**Author:** ![nicolas2b](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/3ab097/32.png) [@nicolas2b](https://www.ruby-forum.com/u/nicolas2b)\ **Post date:** [March 27, 2010, 10:11pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867/3 "2010-03-27T22:11:50Z")
On Sat, Mar 27, 2010 at 10:01 PM, Nicolas 2b [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 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)] =\> [#, #, #, #] irb(main):018:0\> h = Hash.new(0) =\> {} irb(main):020:0\> a.each {|p| h[p[:companyId]] += 1} =\> [#, #, #, #] irb(main):022:0\> h =\> {1=\>2, 2=\>1, 3=\>1} Jesus. ---
**Author:** ![nicolas2b](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/3ab097/32.png) [@nicolas2b](https://www.ruby-forum.com/u/nicolas2b)\ **Post date:** [March 28, 2010, 1:47pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867/4 "2010-03-28T13:47:23Z")
Nicolas 2b wrote: > 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) : > > [#\, #\ 2\>, #\, #\ 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] company\_products = Hash.new(0) products.each { |p| company\_products[p.company\_id] += 1 } p company ---
**Author:** ![nicolas2b](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/3ab097/32.png) [@nicolas2b](https://www.ruby-forum.com/u/nicolas2b)\ **Post date:** [March 27, 2010, 10:55pm UTC](https://www.ruby-forum.com/t/help-to-get-value-from-abject-inside-an-array/185867/5 "2010-03-27T22:55:43Z")
On Sat, Mar 27, 2010 at 3:01 PM, Nicolas 2b [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ## What I want to do is iterate on the array and for each company\_id, know > > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). First, your syntax made it unclear what you wanted in the end, you said an array, but then used hash rockets to indicate key/value pairs. I’m not sure if I got it the way you are needing it. * * * Probably, you should let the database do this for you. Since I don’t know how you are using it, I can’t say for sure, but it sounds like you should be using the SQL count function. The Rails ML will be better equipped to help you. products = Product.all :select =\> ‘company\_id , count(company\_id)’ , :group =\> ‘company\_id’ products.each do |product| company\_id = product.company\_id count = product.attributes[‘count(company\_id)’] puts “#{company\_id} = #{count}” end I’m not sure if there is a nicer way to pull this out than using the attributes hash, but a quick test I ran had it working for me. * * * If using sql isn’t the best option for you, you can do something like this product\_counts = products.group\_by do |product| product.company\_id end product\_counts.each do |company\_id,products| product\_counts[company\_id] = products.size end p product\_counts On Sat, Mar 27, 2010 at 3:04 PM, Nicolas 2b [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ## Sorry for the errors in the title, if someone could correct them :S > > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). The forum is just an interface to a mailing list, you can’t unsend email (well… not really), so you can’t correct them.