B423_quiz.rb

# Q6 - Complete the following code to compute the exact average of students
# grades (using each ).

grades = [19, 8, 11, 15, 13]
sum = 0

# 1) with .each
grades.each { |grade| sum += grade }
p sum.to_f / grades.size


# 2) with .sum
p grades.sum.to_f / grades.size


# 3) with .reduce(:+)
p grades.reduce(:+).to_f / grades.size

# ==============================================================================

# Q11 - Use the map iterator to convert the variable students , an array of
# arrays, into an array of hashes. Those hashes should have two keys: :name and
# :age . What is the type of those keys?


# 1) How do I make an array of hashes? (using .map)

students = [
  ['john', 28],
  ['mary', 25],
  ['paul', 21]
]

hashed_students = students.map do |student_info|
  {
    name: student_info[0],
    age: student_info[1]
  }
end

p hashed_students

# Result:
# [
#   { :name => 'john', :age => 28 },
#   { :name => 'mary', :age => 25 },
#   { :name => 'paul', :age => 21 }
# ]


# 2) How do I convert an array into one hash:

hashed_students = {}
students.each do |student_info|
  hashed_students[student_info[0]] = student_info[1]
end
p hashed_students

# Result:
# { "john" => 28, "mary" => 25, "paul" => 21 }


# 3) Super fancy way of converting and array of arrays into a hash
p students.to_h

# Result:
# { "john" => 28, "mary" => 25, "paul" => 21 }