array exercises

array_filter_map.rb

# Two alternative approaches for https://gist.github.com/peeyush14goyal/506689c0227ff7d7a6071c30f1166a27

todos = [
  ["Send invoice", "money"],
  ["Clean room", "organize"],
  ["Pay rent", "money"],
  ["Arrange books", "organize"],
  ["Pay taxes", "money"],
  ["Buy groceries", "food"]
]

categories = todos.map {|todo| todo[1] }.uniq

# A functional approach
categories.each do |category|
  puts "#{category}:"
  
  todo_names = 
    todos.filter {|todo| todo[1] == category}.
          map {|todo| "  #{todo[0]}"}.
          join("\n")

  puts todo_names
end

# A more imperative approach
categories.each do |category|
  puts "#{category}:"
  todos_for_this_category = todos.filter {|todo| todo[1] == category}
  todos_for_this_category.each do |todo|
    puts "  #{todo[0]}"
  end
end