Building on NDS Exploring Code

1. vm = [[[{:name=>"Vanilla Cookies", :price=>3}, {:name=>"Pistachio Cookies", :price=>3}, {:name=>"Chocolate Cookies", :price=>3}, {:name=>"Chocolate Chip Cookies", :price=>3}], [{:name=>"Tooth-Melters", :price=>12}, {:name=>"Tooth-Destroyers", :price=>12}, {:name=>"Enamel Eaters", :price=>12}, {:name=>"Dentist's Nightmare", :price=>20}], [{:name=>"Gummy Sour Apple", :price=>3}, {:name=>"Gummy Apple", :price=>5}, {:name=>"Gummy Moldy Apple", :price=>1}]], [[{:name=>"Grape Drink", :price=>1}, {:name=>"Orange Drink", :price=>1}, {:name=>"Pineapple Drink", :price=>1}], [{:name=>"Mints", :price=>13}, {:name=>"Curiously Toxic Mints", :price=>1000}, {:name=>"US Mints", :price=>99}]]]
4. row_index = 0
5. while row_index < vm.length do
6. puts "Row #{row_index} has #{vm[row_index]} columns"
8. column_index = 0
9. while column_index < vm[row_index].length do
10. coord = "#{row_index}, #{column_index}"
11. inner_len = vm[row_index][column_index].length
12. # Remember \t is a TAB character for indentation
13. puts "\tCoordinate [#{coord}] points to an #{vm[row_index][column_index].class} of length #{inner_len}"
15. inner_index = 0
16. while inner_index < inner_len do
17. puts "\t\t (#{coord}, #{inner_len}) is: #{vm[row_index][column_index][inner_index]}"
18. inner_index += 1
19. end
21. column_index += 1
22. end
24. row_index += 1
25. end

Outputs:

1. Row 0 has [[{:name=>"Vanilla Cookies", :price=>3}, {:name=>"Pistachio Cookies", :price=>3}, {:name=>"Chocolate Cookies", :price=>3}, {:name=>"Chocolate Chip Cookies", :price=>3}], [{:name=>"Tooth-Melters", :price=>12}, {:name=>"Tooth-Destroyers", :price=>12}, {:name=>"Enamel Eaters", :price=>12}, {:name=>"Dentist's Nightmare", :price=>20}], [{:name=>"Gummy Sour Apple", :price=>3}, {:name=>"Gummy Apple", :price=>5}, {:name=>"Gummy Moldy Apple", :price=>1}]] columns
2. Coordinate [0, 0] points to an Array of length 4
3. (0, 0, 4) is: {:name=>"Vanilla Cookies", :price=>3}
4. (0, 0, 4) is: {:name=>"Pistachio Cookies", :price=>3}
5. (0, 0, 4) is: {:name=>"Chocolate Cookies", :price=>3}
6. (0, 0, 4) is: {:name=>"Chocolate Chip Cookies", :price=>3}
7. Coordinate [0, 1] points to an Array of length 4
8. (0, 1, 4) is: {:name=>"Tooth-Melters", :price=>12}
9. (0, 1, 4) is: {:name=>"Tooth-Destroyers", :price=>12}
10. (0, 1, 4) is: {:name=>"Enamel Eaters", :price=>12}
11. (0, 1, 4) is: {:name=>"Dentist's Nightmare", :price=>20}
12. Coordinate [0, 2] points to an Array of length 3
13. (0, 2, 3) is: {:name=>"Gummy Sour Apple", :price=>3}
14. (0, 2, 3) is: {:name=>"Gummy Apple", :price=>5}
15. (0, 2, 3) is: {:name=>"Gummy Moldy Apple", :price=>1}
16. Row 1 has [[{:name=>"Grape Drink", :price=>1}, {:name=>"Orange Drink", :price=>1}, {:name=>"Pineapple Drink", :price=>1}], [{:name=>"Mints", :price=>13}, {:name=>"Curiously Toxic Mints", :price=>1000}, {:name=>"US Mints", :price=>99}]] columns
17. Coordinate [1, 0] points to an Array of length 3
18. (1, 0, 3) is: {:name=>"Grape Drink", :price=>1}
19. (1, 0, 3) is: {:name=>"Orange Drink", :price=>1}
20. (1, 0, 3) is: {:name=>"Pineapple Drink", :price=>1}
21. Coordinate [1, 1] points to an Array of length 3
22. (1, 1, 3) is: {:name=>"Mints", :price=>13}
23. (1, 1, 3) is: {:name=>"Curiously Toxic Mints", :price=>1000}
24. (1, 1, 3) is: {:name=>"US Mints", :price=>99}

Based on this code and its output, we can slowly step toward a model of how to get the prices we need to add together. As part of our strategy, we're still printing out useful "debug" data to the screen. In that debug data we see a way forward. Instead of printing out:

(1, 0, 3) is: {:name=>"Grape Drink", :price=>1}

we can take the value pointed to by :price and add it to a grand total. We'll build on the code we just demonstrated above, and add a few code comments to help us remember what's happening inside our code.

1. vm = [[[{:name=>"Vanilla Cookies", :price=>3}, {:name=>"Pistachio Cookies", :price=>3}, {:name=>"Chocolate Cookies", :price=>3}, {:name=>"Chocolate Chip Cookies", :price=>3}], [{:name=>"Tooth-Melters", :price=>12}, {:name=>"Tooth-Destroyers", :price=>12}, {:name=>"Enamel Eaters", :price=>12}, {:name=>"Dentist's Nightmare", :price=>20}], [{:name=>"Gummy Sour Apple", :price=>3}, {:name=>"Gummy Apple", :price=>5}, {:name=>"Gummy Moldy Apple", :price=>1}]], [[{:name=>"Grape Drink", :price=>1}, {:name=>"Orange Drink", :price=>1}, {:name=>"Pineapple Drink", :price=>1}], [{:name=>"Mints", :price=>13}, {:name=>"Curiously Toxic Mints", :price=>1000}, {:name=>"US Mints", :price=>99}]]]
4. grand_total = 0
5. row_index = 0
6. while row_index < vm.length do
7. column_index = 0
8. while column_index < vm[row_index].length do
9. inner_len = vm[row_index][column_index].length
10. inner_index = 0
11. while inner_index < inner_len do
12. # Explanation!
13. # vm[row][column][spinner]
14. # spinner is full of Hashes with keys :price and :name
15. grand_total += vm[row_index][column_index][inner_index][:price]
16. inner_index += 1
17. end
18. column_index += 1
19. end
20. row_index += 1
21. end
23. p grand_total #=> 1192

Look at that! It's an insight! All these snacks are worth $1192.00

Lab

In this lab, you're going to work through the directors database and create a Hash that records the director's name as a key, and the total grosses of all of their movies as the value. For example:

1. hash = {
2. "1st Director's Name"=>1234567890,
3. "2nd Director's Name"=>1234577890,
4. "3rd Director's Name"=>1234709136,
5. ...
6. }