Short quiz to test how well you know ruby array methods. See the [blog post](https://www.vector-logic.com/blog/posts/test-yourself-on-ruby-array-operations) to have a go at the quiz

ruby-arrays-quiz.rb

# To test yourself on the actual quiz, see 
# https://www.vector-logic.com/blog/posts/test-yourself-on-ruby-array-operations

def print_question_number(n)
  puts ["="*20, n, "="*20].join("   ")
end

# Array indexing options
print_question_number(1)
arr = ['a', 'b', 'c', 'd', 'e']
puts arr[1]
puts arr.at(1)
begin
  puts arr.fetch('b') # Raises error
rescue StandardError; end
puts arr.find{|i| i=='b' }


# Array selection options
print_question_number(2)
arr = ['a', 'b', 'c', 'd', 'e']
puts arr.select{|i| i=='b' }.map(&:upcase)
begin
  puts arr.find{|i| i=='b' }.map(&:upcase) # Raises error
rescue StandardError; end
puts arr.take(2).last(1).map(&:upcase)
puts arr.sample(3).map(&:upcase)

# Bang operators
print_question_number(3)
arr = ['a', 'b', 'c', 'd', 'e']
arr.map(&:upcase).reject!{|i| i=='B' }
puts arr

# Array initialization options
print_question_number(4)
puts Array.new(4, "a")
puts Array.new(4){|i| "a" }
puts ["a"]*4
puts "aaaa".split

# Array equality operator
print_question_number(5)
puts ["a", 5, "6"]==["a", 5.0, "6"]
puts ["a", nil, 5, "6"].compact==["a", 5.0, "6", nil].compact
puts  ["a", 5, "6"].map(&:to_s)==["a", 5.0, 6].map(&:to_s)
puts ["a", 5, "6"]==["a", 5.0, 6]
puts ["a", 5, "6"]==["a", 5.0, "6", nil]

# Array map, sum, join and split
print_question_number(6)
puts (1...5).map(&:to_s).join('')
puts 12345.to_s.split.sum('')
puts "54321".reverse
puts "54321".split.reverse.join

# Array select, find, join and split
print_question_number(7)
nums = [8, 13, 27, 61, 50].shuffle
puts nums.select{|n| n.even? }
puts nums.find{|n| n.even? }
puts nums.filter{|n| n.even? }
puts [nums[0], nums[-1]]


# Array set operations
print_question_number(8)
puts ['a', 'e', 'f'] | ['b'] & arr # Outputs ['a', 'e', 'f', 'b']

# Array mutation operations
print_question_number(9)
foo  = ['a', 'b', 'c']
foo << "x"  # Appended to end ['a', 'b', 'c', 'x']
foo.shift   # Remove from start of array ['b', 'c', 'x']
foo.append(['d', 'e', 'f']) # Appends full array to last element ['b', 'c', 'x', ['d', 'e', 'f']]
foo.unshift("y") # Pushes y to front of array ['y', 'b', 'c', 'x', ['d', 'e', 'f']]
foo.pop # Removes the array we appended earlier: ['y', 'b', 'c', 'x' ]
puts foo

# Array zip and sort
print_question_number(10)
names = [ "Aodhan", "Domhnall", "Caoimhe", "Blaithin"]
scores = [ 68, 23, 88, 71 ]
puts names.zip(scores).sort_by{|el| el[1] }.last[0] # Should return the person associated with the highest score, i.e. Siobhan