# Zhi Yuan "Oscar" Lin # 29 October 2021 # In this lesson, it was mainly review of what was taught in the previous lessons. The following are some examples of what # were reviewed: commenting, creating a list, slicing a list, using the list methods (".append()", ".insert()", ".reverse," # and ".pop"), defining and calling a function, initializing and using a variable, using relational operators, using a while # loop, using the "return" and "del" keywords, and using built-in functions ("print()" and "input()"). # There were no major problems or questions throughout this lesson.

# [ ] create and populate list called days_of_week then print it # The variable "days_of_week" is assigned to a list of strings. days_of_week = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"] # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] after days_of_week is run above, print the days in the list at odd indexes 1,3,5 # This function only displays the 2nd element of the value assigned to the days_of_week variable along with the characters # that are every two places after the 2nd element until the last element, in the output. In this case, the 4th and 6th # element will also be display in the output. print(days_of_week[1:7:2])

# [ ] create and populate list called phone_letters then print it # The variable "phone_letters" is assigned to a list of strings. phone_letters = [' ', "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ"] # This function displays the string assigned phone_letters variable in the output. print(phone_letters)

# [ ] create a variable: day, assign day to "Tuesday" using days_of_week[] # [ ] print day variable # The variable "day" is assigned to the element that is within the index position 1 in the value assigned to the # days_of_week variable. day = days_of_week[2] # This function displays the value assigned to the day variable in the output. print(day)

# PART 2 # [ ] assign day to days_of_week index = 5 # [ ] print day # The variable "day" is assigned to the element that is within the index position 5 in the value assigned to the # days_of_week variable. day = days_of_week[5] # This function displays the value assigned to the day variable in the output. print(day)

# [ ] Make up a new day! - append an 8th day of the week to days_of_week # [ ] print days_of_week # This line of code adds the string "Doomsday" to the end of the value assigned to the days_of_week variable due to the # list method ".append()". days_of_week.append("Doomsday") # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] Make up another new day - insert a new day into the middle of days_of_week between Wed - Thurs # [ ] print days_of_week # The variable "day" is assigned to the string "Pancakeday". day = "Pancakeday" # This line of code inserts the value assigned to the day variable into the index positon 3 of the value assigned to the # days_of_week variable. days_of_week.insert(4, day) # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] Extend the weekend - insert a day between Fri & Sat in the days_of_week list # [ ] print days_of_week # The variable "day" is assigned to the string "Syrupday". day = "Syrupday" # This line of code inserts the value assigned to the day variable into the index positon of the value assigned to the # days_of_week variable. days_of_week.insert(7, day) # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] print days_of_week # [ ] modified week is too long - pop() the last index of days_of_week & print .pop() value # [ ] print days_of_week # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week) # This function displays the element that was removed from the value assigned to the days_of_week variable due to the # list method ".pop()". In this case, the the value in the last index position in the value assigned to the party_list # is removed due to the list method".pop()" not having an index specified. print(days_of_week.pop()) # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] print days_of_week # [ ] delete (del) the new day added to the middle of the week # [ ] print days_of_week # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week) # This line of code deletes the element that is within the index position 4 in the value assigned to the days_of_week # variable. del days_of_week[4] # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] print days_of_week # [ ] programmers choice - pop() any day in days_of week & print .pop() value # [ ] print days_of_week # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week) # This function displays the value assigned to the days_of_week variable after the element in the index position 1 in the # value assigned to the days_of_week is removed due to the list method ".pop()". print(days_of_week.pop(1)) # This function displays the value assigned to the days_of_week variable in the output. print(days_of_week)

# [ ] create let_to_num() # This program defines a function named "let_to_num" with the variable "letter", that will be assign to the entry the user # inputs when presented with the string "Single letter, space or empty string: ". Additionally, the variable "key" is # assigned to the integer "0". The function also contains a while loop. In this case, the while loop is follow by the # statement "key < 10". Hence, it cannot evaluate anything but true. Additionally, the codes that are indented and follow # the while loop will be part of the loop. Thus, the loop starts with determining if the value assigned to the letter # variable, after being changed into uppercases due to the letter variable being attached to the string method ".upper()", # is in the value, that is the index position given from value assigned to the key variable, assigned to the phone_letters # variable. If true, the value assigned to the key variable will be return by the return keyword and the loop will end. If # false, the program moves on to the else statement with the key variable being reassigned to the sum of the value assigned # to the key variable incremented by 1. If no value is return by the return keyword, this loop will continue until the # statement "key < 10" is false. When the loop ends, the string "Not Found" will be return by the return keyword. def let_to_num(): letter = input("Single letter, space or empty string: ") key = 0 while key < 10: if letter.upper() in phone_letters[key]: return key else: key = key + 1 return "Not Found" # This function displays the returned value when calling the let_to_num() function, in the output. print(let_to_num())

# [ ] Challenge: write the code for "reverse a string from a list" # The variable "str" is assigned to a list of strings. str = ["French Toast", "Pancakes", "Waffles", "Bagel", "Muffin"] # The variable "rev_str" is assigned to an empty list. rev_str = [] # This function displays the string "List before:" and the value assigned to the str variable in the output. print("List before:", str) # In this case, the while loop is follow by the variable "str". Hence, as long as a value is assigned to the str variable, # it will evaluate true. Additionally, the codes that are indented and follow the while loop will be part of the loop. # Thus, the loop starts with the substring, that is in the index position 0 of the value assigned to the str variable, being # removed and assigned to the rev variable, due to the list method ".pop()". Subsequently, the value assigned to the rev # variable will be inserted into the index positon 0 of the value assigned to the rev_str variable, due to the list method # ".insert()". This loop will continue until it evaluates false. while str: rev = str.pop(0) rev_str.insert(0,rev) # This function displays the string "List after:" and the value assigned to the str variable in the output. print("List after:", str) # This function displays the string "Reversed list:" and the value assigned to the rev_str variable in the output. print("Reversed list:", rev_str)