Ruby/Hash/Hash Creation

# you can index it using text strings as well as numbers.
# To create a hash, you use curly braces, { and }, not square braces ([]) as with arrays. 
money = {"Dan" => "$1,000,000", "Mike" => "$500,000"}
# "Dan" is a hash key 
# "$1,000,000" is the value. 
# The => operator separates the keys from the values.

h = Hash.new("Go Fish")
h["a"] = 100
h["b"] = 200
h["a"]  100
h["c"]  
# The following alters the single default object
h["c"].upcase!  
h["d"]  
h.keys

h = Hash.new {|hash, key| hash[key] = "Go Fish: #{key}" }
h["c"]  
h["c"].upcase!  
h["d"]  
h.keys

h = Hash.new("nope")
p h[1]                                           # => "nope"
p h["do you have this string?"]                   # => "nope"

h = { "a" => 100, "b" => 200 }
h["a"] = 9
h["c"] = 4
puts h

fruit = {
  :apple => "fruit",
  :orange => "fruit",
  :squash => "vegetable"
}
puts fruit[:apple]
fruit[:corn] = "vegetable"
puts fruit[:corn]

myHash = Hash[ :name, "Jack", :partner, "Jane", :employee, "Joe", :location, "London", :year, 1843 ]

month_a = { "jan" => "January", "feb" => "February", "mar" => "March", "apr"

Each value is associated (=>) with a key. 
One of the ways you can access the values in a hash is by their keys. 
pacific = { "WA" => "Washington", "OR" => "Oregon", "CA" => "California" }
 
pacific["OR"] # => "Oregon"

pizza = {"first_topping" => "pepperoni", "second_topping" => "sausage"}
p pizza["first_topping"]
p pizza
p pizza.length
receipts = {"day_one" => 5.03, "day_two" => 15_003.00}
p receipts["day_one"]
p receipts["day_two"]

receipts = {"day_one" => 5.03, "day_two" => 15_003.00}
puts receipts["day_one"]
puts receipts["day_two"]