Return a unique array of values from array of hashes

Question

I have an array @contacts of hashes, each of which has the following keys:

:full_name
:city
:state
:email

How would I iterate through the array to return the :city values uniquely? Below is my best attempt

@contacts.uniq {|hash| hash[:city]}

Answer 1

@contacts.map { |k| k[:city] }.uniq