Ruby 03-Array-Blocks Lecture

01-arrays.rb

# Ranges

range_1 = (1..10) # includes the last
p range_1

range_2 = (1...10) # does not include the last
p range_2.to_a

# Arrays
movies_stars = [
  "Nicole Kidman",
  "Kurt Russel",
  "Johnny Depp",
  "Jennifer Lawrence"
]

p movies_stars

# Alternative array of strings syntax
# %w[nicole\ kidman kurt\ russel]


puts movies_stars.length
# alternative: #size #count

# movies_stars.push("Leonardo DiCaprio")
movies_stars << "Leonardo DiCaprio"
p movies_stars

# Reading
puts movies_stars[3]

# Updating
movies_stars[3] = "Drew Barrymore"
p movies_stars

puts movies_stars.last
# movies_stars[-1]
# movies_stars[movies_stars.length - 1]

# insert at a specific index
movies_stars.insert(3, "Brad Pitt")
p movies_stars


# iterate over indexes with for
# for i in Array/Range
#   # Do something
# end

for index in 0...movies_stars.length
  movie_star = movies_stars[index]
  puts "#{index + 1} - Star: #{movie_star}"
end

for movie_star in movies_stars
  puts "Watching a movie with #{movie_star}!"
end

02-iterators.rb

# Arrays
movies_stars = [
  "nicole kidman",
  "kurt russel",
  "johnny depp",
  "jennifer lawrence"
]

# capitalized_stars = []
# movies_stars.each do |movie_star|
#   # names = movie_star.split
#   # first_name = names.first
#   # last_name = names.last

#   first_name, last_name = movie_star.split
#   capitalized_stars << "#{first_name.capitalize} #{last_name.capitalize}"
# end


# #map => returns a transformed array of the
# same size as the original array

capitalized_stars = movies_stars.map do |movie_star|
  # names = movie_star.split
  # first_name = names.first
  # last_name = names.last

  first_name, last_name = movie_star.split
  "#{first_name.capitalize} #{last_name.capitalize}"
end

p capitalized_stars

puts "List of Movie Stars:"
#                                       element ,  index
movies_stars.each_with_index do |movie_star, index|
  puts "#{index + 1}) #{movie_star}"
end

# movies_stars.each { |movie_star| puts "Hello, #{movie_star}!" }

# count
j_movie_stars = movies_stars.count do |movie_star|
  movie_star.downcase.start_with?("j")
end
p j_movie_stars

# count
k_movie_stars = movies_stars.count do |movie_star|
  last_name = movie_star.split.last
  last_name.downcase.start_with?("k")
end
p k_movie_stars


# counter = 0
# movies_stars.each do |movie_star|
#   condition = movie_star.downcase.start_with?("j")
#   counter += 1 if condition
# end
# p counter

# find => returns the first element
# that matches the condition

# select => returns all the elements
# that match the condition

movie_stars_with_j_first_name = movies_stars.select do |movie_star|
  movie_star.downcase.start_with?("j")
end
p movie_stars_with_j_first_name

03-blocks.rb

def big_sort
  (0..10000000).sort
end

def small_sort
  (0..1000000).sort
end

def timer
  start_time = Time.now

  # call big_sort
  # big_sort
  yield if block_given?# execute the block

  end_time = Time.now

  puts end_time - start_time
end

timer do
  (0..10000000).sort
end
timer { small_sort }

def greet(name)
  capitalized_name = name.capitalize

  puts "[DEBUG] Starting the block"

  yield(capitalized_name) # execute block

  puts "[DEBUG] Block has been completed!"
end


greet("beatrix") do |name|
  puts "Hello, #{name}!"
end

greet("michael") do |name|
  puts "Good morning, #{name}!"
  puts "How are you?"
end

04-my_each.rb

def my_each(array)
  for element in array
    # Do something
    yield(element)
  end

  array
end

names = ["beatrix", "michael"]

#               yielded element
my_each(names) do |name|
  puts "Hello, #{name.capitalize}"
end