extracting data from a hash of arrays in ruby

Question

I'm new to ruby and working on a large data project and I'v got a nooby question.

I'v got a hash containing data of sales which is sorted by stores id:

hash = Hash.new(Array.new)) Sale.all.each {|sale| hash[sale.store_id].push( JSON.parse(sale.data)['items']) }

Now, I want to run over each store_id and get every item.promo_code = 24 and say how many item are there for each store.id.

Here is the data structure of the array inside of each key:

hash => 1 : Array [[{DATA,DATA,DATA}{DATA,DATA,DATA}]]

How would this be done in ruby?

Thank you very much in advance

EDIT:

I decided to attack this problem from a different angle

Sale.all.each {|sale| arr[sale.store_id] +=1 if (JSON.parse(sale.data)['items'].each{|item| item['buy_promotion_code']} == 24) }

doesn't get me anything i get arr[#] = 0 all the time help : (

Please improve your question by including whatever samples you're using as a corpus to test against. Also, include a properly-formatted sample of your expected output so folks understand the results you're trying to achieve. — Todd A. Jacobs
– Todd A. Jacobs, Commented Feb 23, 2014 at 16:47

nickcen · Accepted Answer · 2014-02-23 09:08:21Z

1

result_hash = {} hash.each do |key, array| result_hash[key] = array.find_all({|item| item.promo_code = 24}).length end

answered Feb 23, 2014 at 9:08

nickcen

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3 Comments

DrDark Over a year ago

this seems like its supposed to work but i still get result_hash[key]= nil :(

nickcen Over a year ago

It may relative to the data structure inside the hash instance. According to your description the data inside the hash may have the structure like this. {:1 => [{:promo_code => 1}, {:promo_code => 2}, ...], :2 => [{:promo_code => 1}, {:promo_code => 24}, ...], ...}. Check it out of your hash instance and see whether this is right.

DrDark Over a year ago

i posted more info maybe you can help me ? : )

Raj · Accepted Answer · 2014-02-23 09:04:13Z

result_hash = {} hash.each do |key, array| result_hash[key] += 1 if array[0] == 24 puts array end

where array[0] should give the value of promo_code of each item in the array.

DrDark · Accepted Answer · 2014-02-24 08:16:59Z

My friend helped me with this.

he showed me the count function which simplified all this mess

this is the line that worked for me :

Sale.all.each {|sale| arr[sale.store_id] += (JSON.parse(sale.data)['items'].count {|item| item['buy_promotion_code'] == "-1"}) }

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