# Zhi Yuan "Oscar" Lin # 24 October 2021 # In this lesson, I learned more about the del statement, and the list methods, ".pop()" and ".remove()", through examples # and tasks. Additionally, I learned a new error called, "ValueError". # There were no major problems or questions throughout this lesson.

# [ ] review and run example # the list before delete # The variable "sample_list" is assigned to a list of integers. sample_list = [11, 21, 13, 14, 51, 161, 117, 181] # This function displays the string "sample_list before: " and the value assigned to the sample_list variable in the output. print("sample_list before: ", sample_list) # This line of code deletes the value in the index position 1 in the value assigned to the sample_list variable due to the # keyword "del". del sample_list[1] # the list after delete # This function displays the string "sample_list after: " and the value assigned to the sample_list variable in the output. print("sample_list after: ", sample_list)

# [ ] review and run example Multiple Times # [ ] consider how to reset the list values? # Answer: Run the program above to reset the list values. # This function displays the string "sample_list before: " and the value assigned to the sample_list variable in the output. print("sample_list before:", sample_list) # This line of code deletes the value in the index position 0 in the value assigned to the sample_list variable due to the # keyword "del". del sample_list[0] # This function displays the string "sample_list after: " and the value assigned to the sample_list variable in the output. print("sample_list after:", sample_list)

# [ ] review and run example # The variable "mixed_types" is assigned to a list of mixed data types. mixed_types = [1, "cat"] # append number # This line of code adds the integer "3" to the end of the value assigned to the mixed_types variable. mixed_types.append(3) # This function displays the string "mixed_types list: " and the value assigned to the mixed_types variable in the output. print("mixed_types list: ", mixed_types) # append string # This line of code adds the string "turtle" to the end of the value assigned to the mixed_types variable. mixed_types.append("turtle") # This function displays the string "mixed_types list: " and the value assigned to the mixed_types variable in the output. print("mixed_types list: ", mixed_types)

# [ ] print ft_bones list # [ ] delete "cuboid" from ft_bones # [ ] reprint list # The variable "ft_bones" is assigned to a list of strings. ft_bones = ["calcaneus", "talus", "cuboid", "navicular", "lateral cuneiform", "intermediate cuneiform", "medial cuneiform"] # This function displays the value assigned to the ft_bones variable in the output. print(ft_bones) # This line of code deletes the string "cuboid" from the value assigned to the ft_bones variable due to the keyword "del". del ft_bones[2] # This function displays the value assigned to the ft_bones variable in the output. print(ft_bones)

# [ ] print ft_bones list # [ ] delete "cuboid" from ft_bones # [ ] delete "navicular" from list # [ ] reprint list # [ ] check for deletion of "cuboid" and "navicular" # The variable "ft_bones" is assigned to a list of strings. ft_bones = ["calcaneus", "talus", "cuboid", "navicular", "lateral cuneiform", "intermediate cuneiform", "medial cuneiform"] # This function displays the value assigned to the ft_bones variable in the output. print(ft_bones) # This line of code deletes the string "cuboid" from the value assigned to the ft_bones variable due to the keyword "del". del ft_bones[2] # This line of code deletes the string "navicular" from the value assigned to the ft_bones variable due to the keyword "del". del ft_bones[2] # This function displays the value assigned to the ft_bones variable in the output. print(ft_bones)

# [ ] review and run example # pop() gets the last item by default # The variable "party_list" is assigned to a list of strings. party_list = ["Joana", "Alton", "Tobias"] # This function displays the value assigned to the party_list variable in the output. print(party_list) # This function displays the string "Hello" and the value assigned to the party_list variable in the output, after the value # in the last index position in the value assigned to the party_list is removed by the list method ".pop()", that does not # have an index specified. print("Hello,", party_list.pop()) # This function displays the value assigned to the party_list variable in the output. Additionally, before the value is # displayed there will be a blank line displayed in the previous line in the output due to the escape character "\n". print("\n", party_list) # This function displays the string "Hello" and the value assigned to the party_list variable in the output, after the value # in the last index position in the value assigned to the party_list is removed by the list method".pop()", that does not # have an index specified. print("Hello,", party_list.pop()) # This function displays the value assigned to the party_list variable in the output. Additionally, before the value is # displayed there will be a blank line displayed in the previous line in the output due to the escape character "\n". print("\n", party_list) # This function displays the string "Hello" and the value assigned to the party_list variable in the output, after the value # in the last index position in the value assigned to the party_list is removed by the list method ".pop()", that does not # have an index specified. print("Hello,", party_list.pop()) # This function displays the value assigned to the party_list variable in the output. Additionally, before the value is # displayed there will be a blank line displayed in the previous line in the output due to the escape character "\n". print("\n", party_list)

# [ ] review and run example # can pop specific index like pop(3) # The variable "number_list" is assigned to a list of integers. number_list = [11, 21, 13, 14, 51, 161, 117, 181] # This function displays the string "before:" and the value assigned to the number_list variable in the output. print("before:", number_list) # This line of code just removes the value in the index position 3 in the value assigned to the number_list variable due # to the list method".pop()". number_list.pop(3) # This function displays the string "after :" and the value assigned to the number_list variable in the output. print("after :", number_list)

# [ ] review and run example # set a variable to a poped value # The variable "number_list" is assigned to a list of integers. number_list = [11, 21, 13, 14, 51, 161, 117, 181] # This function displays the string "list before:" and the value assigned to the number_list variable in the output. print("list before:", number_list) # This line of code removes the last value in the value assigned to the number_list variable, because there is no # index specified, and assigned it to the variable "num_1" due to the list method ".pop()". num_1 = number_list.pop() # This line of code removes the last value in the value assigned to the number_list variable, because there is no # index specified, and assigned it to the variable "num_2" due to the list method ".pop()". num_2 = number_list.pop() # This function displays the string "list after:" and the value assigned to the number_list variable in the output. print("list after :", number_list) # This function displays the string "add the popped values:", the value assigned to the num_1 variable, the string "+", the # value assigned to the num_2 variable, the string "=", and the sum of the value assigned to the num_1 variable and the # value assigned to the num_2 variable, in the output. print("add the popped values:", num_1, "+", num_2, "=", num_1 + num_2)

# [ ] pop() and print the first and last items from the ft_bones list # The variable "ft_bones" is assigned to a list of strings. ft_bones = ["calcaneus", "talus", "cuboid", "navicular", "lateral cuneiform", "intermediate cuneiform", "medial cuneiform"] # This line of code removes the value in the index position 0 in the value assigned to the ft_bones variable due to # the list method ".pop()". ft_bones.pop(0) # This line of code removes the last value in the value assigned to the ft_bones variable, because there is no # index specified, due to the list method ".pop". ft_bones.pop() # [ ] print the remaining list # This function displays the value assigned to the ft_bones variable in the output. print(ft_bones)

# The variable "dog_types" is assigned to a list of strings. dog_types = ["Lab", "Pug", "Poodle"] # In this case, the while loop is followed by the variable "dog_types". Hence, as long the list assigned to the dog_types # variable is not empty 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 displaying the last value in the value assigned to the dog_types variable, # that is removed due to the list method ".pop()" not having an index specified, in the output. This loop will continue # until the list assigned to the dog_types variable is empty. while dog_types: print(dog_types.pop())

#[ ] complete the Register Input task above # The variable "purchase_amounts" is assigned to an empty list. purchase_amounts = [ ] # In this case, the while loop is written with the keyword "True". 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 the variable # "price" that will be assigned to the entry the user inputs when presented with the string "Enter the price of the items # (or "done" to end): ". Subsequently, there is an IF statement that determines if the value assigned to the price variable # is all digits by using the string method ".isdigit()". If true, the value assigned to the price variable will be added # to the value assigned purchase_amounts variable due to the ".append()" method. If false, the program moves on to the elif # statement and determines if the value assigned to the price variable is equal to, ==, the string "done" after being # changed into all lowercases due to the price variable being attached to the string method ".lower()". If true, the loop # will end due to the following keyword "break". If false, the program moves on to the else statement with the string # "Invalid input", that is within the parentheses of the print() function, being display in the output. while True: price = input('Enter the price of the items (or "done" to end): ') if price.isdigit(): purchase_amounts.append(price) elif price.lower() == 'done': break else: print("Invalid input") # This function displays the value assigned to the purchase_amounts variable in the output. print(purchase_amounts)

# [ ] complete the Register Total task above # The variable "subtotal" is assigned to the integer "0". subtotal = 0 # In this case, the while loop is followed by the variable "purchase_amounts". Hence, as long the list assigned to the # purchase_amounts variable is not empty 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 variable "value" being assigned to the last value # that was removed from the value assigned to the to the purchase_amounts variable by the ".pop()" method, after it is # changed into a float due to it being within the parentheses of the float() function. Subsequently, the subtotal variable # will be reassigned to the sum of the value assigned to the subtotal variable and the value assigned to the value # variable. while purchase_amounts: value = float(purchase_amounts.pop()) subtotal += value # This function displays the value assigned to the subtotal variable in the output. print(subtotal)

# [ ] review and run example # The variable "dog_types" is assigned to a list of strings. dog_types = ["Lab", "Pug", "Poodle"] # This IF statement determines if the string "Pug" is within the value assigned to the dog_variable variable by using the # keyword "in". If true, the string "Pug" will be removed from the value assigned to the dog_types variable by the list # method ".remove()". If false, the program moves on to the else statement with the string "no Pug found", that is within # the parentheses of the print() function, being display in the output. if "Pug" in dog_types: dog_types.remove("Pug") else: print("no Pug found") # This function displays the value assigned to the dog_types variable in the output. print(dog_types)

# [ ] review and run example # The variable "dogs" is assigned to a list of strings. dogs = ["Lab", "Pug", "Poodle", "Poodle", "Pug", "Poodle"] # This function displays the value assigned to the dogs variable in the output. print(dogs) # In this case, the while loop is followed by the the statement '"Poodle" in dogs'. Hence, as long the string "Poodle" is # within the value assigned to the dogs 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 first string "Poodle" the program # identifies being removed from the value assigned to the dogs variable by the list method ".remove()". Subsequently, # the value assigned to the dogs variable will be display in the output. This loop will continue until the string "Poodle" # is no longer found within the value assigned to the dogs variable. while "Poodle" in dogs: dogs.remove("Poodle") print(dogs)

# [ ] review and run example # Change to "Lab", etc... to fix error # This program originally contained a ValueError due to the list method ".remove()" trying to remove the string "Collie" # from the value that is assigned to dogs variable when there is no "Collie" within the value. This error is fixed by # replacing the string "Collie" with a string that is within the value assigned to the dogs variable. # This line of code removes the string "Lab" that is within the value that is assigned to the dogs variable. dogs.remove("Lab") # This function displays the value assigned to the dogs variable in the output. print(dogs)

# [ ] remove one "Poodle" from the list: dogs , or print "no Poodle found" # [ ] print list before and after # The variable "dogs" is assigned to a list of strings. dogs = ["Lab", "Pug", "Poodle", "Poodle", "Pug", "Poodle"] # This function displays the string "list before: " and the value assigned to the dogs variable in the output. print("list before: ", dogs) # This IF statement determines if the string "Poodle" is within the value assigned to the dogs variable by using the # keyword "in". If true, the first string "Poodle" the program identifies will be remove by the list method ".remove()". # If false, the program moves on to the else statement with the string "no Poodle found", that is within the parentheses # of the print() function, being display in the output. if "Poodle" in dogs: dogs.remove("Poodle") else: print("no Poodle found") # This function displays the string "list after: " and the value assigned to the dogs variable in the output. print("list after: ", dogs)