Array of hashes to hash

Question

For example, I have array of single hashes

a = [{a: :b}, {c: :d}] 

What is best way to convert it into this?

{a: :b, c: :d} 

Answer 1

You may use

a.reduce Hash.new, :merge 

which directly yields

{:a=>:b, :c=>:d} 

Note that in case of collisions the order is important. Latter hashes override previous mappings, see e.g.:

[{a: :b}, {c: :d}, {e: :f, a: :g}].reduce Hash.new, :merge   # {:a=>:g, :c=>:d, :e=>:f} 

Answer 2

You can use .inject:

a.inject(:merge) #=> {:a=>:b, :c=>:d} 

Demonstration

Which initiates a new hash on each iteration from the two merged. To avoid this, you can use destructive :merge!( or :update, which is the same):

a.inject(:merge!) #=> {:a=>:b, :c=>:d} 

Demonstration