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Stripping Duplicate Elements from an Array
CodeExpectedActual
survey_results = [1, 2, 7, 1, 1, 5, 2, 5, 1]
distinct_answers = survey_results.uniq
 [1, 2, 7, 5] [1, 2, 7, 5] 
survey_results.uniq!
survey_results
 [1, 2, 7, 5] [1, 2, 7, 5] 
require 'set'
survey_results = [1, 2, 7, 1, 1, 5, 2, 5, 1]
distinct_answers = survey_results.to_set
 #<Set: {5, 1, 7, 2}> #<Set: {5, 1, 7, 2}> 
games = [["Alice", "Bob"], ["Carol", "Ted"], 
         ["Alice", "Mallory"], ["Ted", "Bob"]]
players = games.inject(Set.new) { |set, game| game.each { |p| set << p }; set }
 #<Set: {"Alice", "Mallory", "Ted", "Carol", "Bob"}> #<Set: {"Alice", "Mallory", "Ted", "Carol", "Bob"}> 
players << "Ted"
 #<Set: {"Alice", "Mallory", "Ted", "Carol", "Bob"}> #<Set: {"Alice", "Mallory", "Ted", "Carol", "Bob"}> 
class OrderedSet < Set
  def initialize
    @hash ||= OrderedHash.new
  end
end
a = [1, 2, nil, 3, 3, nil, nil, nil, 5]
a.compact
 [1, 2, 3, 3, 5] [1, 2, 3, 3, 5] 
a.delete(3)
a
 [1, 2, nil, nil, nil, nil, 5] [1, 2, nil, nil, nil, nil, 5]