From: "Jan E." <lists@...>
Date: 2012-11-07T01:14:06+09:00
Subject: Re: How to merge two or more hashes in to one?

Jermaine O. wrote in post #1083159:
> Hi Jan, I appreciate your help but care to give an example?

I suppose you have an array of hashes. Define a variable for the 
intermediate results and initialize it with an empty hash. Then you loop 
through the hashes and merge each one with the intermediate hash:

#-------------------------
data = [
  {luxury: ["Mercedes", "BMW"], sport: ["Ferrari"]},
  {luxury: ["BMW", "Bentley"], sport: ["Lamborghini"]},
  {luxury: ["something luxury"], sport: ["something sporty"]},
]

merged = {}
data.each do |cars|
  merged.merge!(cars) {|_, v_1, v_2| v_1 | v_2}
end
p merged
#-------------------------

The same thing can be achieved with Enumerable#inject, which is the 
generalization of this kind of "sum up the elements of a collection":

#-------------------------
merged = data.inject do |cars_1, cars_2|
  cars_1.merge(cars_2) {|_, v_1, v_2| v_1 | v_2}
end
p merged
#-------------------------

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