panpsychism/ruby_rails_sql_resources/morning_Ex/basic_ruby.md

BASIC RUBY REFRESHER

Strings

Perform the following tasks using string methods:

1. Reverse the string, "sarcophagus".
2. Return the substring, "undulating", from the string, "Are these artichokes undulating?".
3. Convert the string, "90210", to an integer.
4. Capitalize the letter "m" in the string "meeseeks".
5. Capitalize all of the letters in the string "Capitalize all of the letters in the string".

Arrays and Loops

NOTES

.each and .map

You can use .each as a basic loop for pushing values into arrays or sending out transforms without altering the original array. For example, given the following dataset:

arr1 = ["moops", "cherish the cabin"]
arr2 = []

.each for pushing into another array.
Note: << is the same as .push()

arr1.each { |item| arr2 << item.upcase }
p arr2

=> ["MOOPS", "CHERISH THE CABIN"]

This is the expanded version using do and end instead of curlies:

arr1.each do |item|
	arr2 << item.upcase
end

=> ["MOOPS", "CHERISH THE CABIN"]

.map, by contrast, returns a transform of the dataset:

new_set = arr1.map { |item| item.upcase }
p new_set

=> ["MOOPS, CHERISH THE CABIN"]

.each will not do a transform:

new_set = arr1.each { |item| item.upcase }
p new_set
  
=> ["moops", "cherish the cabin"]

EXERCISE

Perform the following tasks using array methods (note: you might also need to use some string methods): Switch it up between .map and .each and any others you might find in the docs.

1. Given the array numbers = [1, 3, 5, 7], use map to create a new array with each element of numbers multiplied by three. Do it once with do .. end and once with curlies.

2. Save a shuffled version of this array to a variable just to see how easy it is to do so.

3. Give the array names = ["Joe, Matt, Thom"] use each to iterate over each word and print it to the console with " is my friend and contemporary." appended. Do it once with do .. end and again with curlies.

4. Given the following array (of arrays):

sandwiches_with_costs = [["blt", 5], ["grilled cheese", 7], ["turkey_club_with_pesto", 9], ["ramenburger", 6], ["portobello and garlic aioli", 10]]

Create an empty hash (call it whatever you want) and then iterate over sandwiches_with_costs and add sandwich names as keys and cost amounts as values to the hash.

Hashes

Perform the following tasks using hash methods (note: you might also need to use some string and array methods).

Given the hash:

breakfast_prefs = {
  juice: "orange",
  syrup: "maple",
  potatoes: "mashed with molasses",
  lettuce: "iceberg",
  protein: "GNC Pro Performance AMP Amplified Wheybolic Extreme 60™ Original",
  cups_of_coffee: 3,
  pink_slime: false
}

1. Return an array containing only the keys of breakfast_prefs.
2. Return an array containing only the values of breakfast_prefs.
3. Change the value of :syrup to "boysenberry".
4. Return a hash with the key-value pairs whose value is of type string.