Group hashes by keys and sum the values

Question

I have an array of hashes:

[{\"Vegetable\"=>10}, {\"Vegetable\"=>5}, {\"Dry Goods\"=>3>}, {\"Dry Goods\"=>2}]

I need to use

Answer 1

I'm not sure that a hash is what you want here, because I don't multiple entries in each hash. so I'll start by changing your data representation a little.

ProductCount=Struct.new(:name,:count)
data = [ProductCount.new("Vegetable",10),
        ProductCount.new("Vegetable",5),
        ProductCount.new("Dry Goods",3),
        ProductCount.new("Dry Goods",2)]

If the hashes can have multiple key-value pairs, then what you probably want to do is

data = [{"Vegetable"=>10}, {"Vegetable"=>5}, {"Dry Goods"=>3>}, {"Dry Goods"=>2}]
data = data.map{|h| h.map{|k,v| ProductCount.new(k,v)}}.flatten

Now use the facets gem as follows

require 'facets'
data.group_by(&:name).update_values{|x| x.map(&:count).sum}

The result is

{"Dry Goods"=>5, "Vegetable"=>15}