Evolve from .each with these helpful enumerables

|map|

---

Ruby's #map is an extremely useful upgrade from using #each. Not only is it less code to write but it also looks much cleaner. Check out these examples of what #map can do in the place of #each.

  rainbow = ["red", "orange", "yellow", "green", "blue", "purple"]

  colors = []
  rainbow.each{ |color| colors << color.upcase }
  colors
  # returns ["RED", "ORANGE", "YELLOW", "GREEN", "BLUE", "PURPLE"]


  rainbow.map{ |color| color.upcase }
  # returns ["RED", "ORANGE", "YELLOW", "GREEN", "BLUE", "PURPLE"]

Pretty cool right! Ruby's #map returns a new array without changing the original one. If you were to use #each you would need to create an empty array to shovel or push the altered values into. You can use map to grab all of the things!

---

|select|

---

What if you just wanted to grab specific things instead of mapping all of the things? Well you actually can with #select!

   colors = []
   rainbow.each do |color| 
     if color.length > 5
       colors << color
     end
   end
   colors
   # returns ["orange", "yellow", "purple"]


   rainbow.select{ |color| color.length > 5 }
   # returns ["orange", "yellow", "purple"]  

In this example we only grab colors with a length greater than 5. When using #select a new array will be created and populated with the values we specify.

---

|max_by|

---

What if you want to grab the largest thing? You can use #max_by to grab the max value of something.

   rainbow = ["red", "orange", "yellow", "green", "blue", "purpleee"]

   longest = ""
   rainbow.each do |color|
     if color.length > longest.length
       longest = color
     end
   end
   longest
   # returns "purpleee"


   rainbow.max_by{ |color| color.length }
   # returns "purpleee"

You can also specify how many values you want returned. The values returned are similar to using #sample so the order will be random.

   rainbow = ["red", "orange", "yellow", "green", "blue", "purple"]

   colors = []
   longest = ""
   second_longest = ""
   third_longest = ""
   rainbow.each do |color|
     if color.length >= longest.length
       third_longest = second_longest
       second_longest = longest
       longest = color
     end
   end
    colors.push(longest, second_longest, third_longest)
    colors
    # returns ["purple", "orange", "yellow"]


   rainbow.max_by(3){ |color| color.length }
   # returns ["purple", "orange", "yellow"]

If our array looked like this ["red", "orange", "yellow", "greenn", "blue", "purple"] then any combination of 3 of these ["yellow", "greenn", "orange", "purple"] could have been returned.

---

|include?|

---

What if we wanted to find out if our rainbow array has a certain color? We can do that by using #include?.

   rainbow.each do |color| 
     if color == "purple" 
       true
     else
       false
     end
   end
   # returns true


   rainbow.include?("purple")
   # returns true

   rainbow.include?("pink")
   # returns false

Keep in mind that include? returns true or false and not a new array.

---

The magic of & with enumerables.

We can even use this shorthand with enumerables when we don't need to pass in any arguments. This really blew my mind when I found out about it.

   rainbow.map(&:upcase)
   # take note that the usual squigglys{} are now parentheses().
   # returns ["RED", "ORANGE", "YELLOW", "GREEN", "BLUE", "PURPLE"]