# Noemi Cabrera # 27 October 2021 # In this lesson, I learned how to modify and insert items into a list. To modify or # overwrite an existing index in a list, you use = with the item you want to add after # you have sliced and indicated the index you want to replace.To insert an item you use # the .insert() method in which you indicate at which index you want add your item # followed by the item you want to add. # I didn't have any difficulties in this lesson.

# [ In this code, an item in the variable party list is replaced. You do a slice with the # index you want to replace and then you set that equal to what you want to replace it # with. In this case, Alton is replaced with Collete. ] review and run example # the list before Insert party_list = ["Joana", "Alton", "Tobias"] print("party_list before: ", party_list) # the list after Insert party_list[1] = "Colette" print("party_list after: ", party_list)

# [ In this code, the string at index 1 from party_list is added another string. "Alton" equals to itsefl # plus "Derosa", it's not replaced. ] review and run example party_list = ["Joana", "Alton", "Tobias"] print("before:",party_list) # modify index value party_list[1] = party_list[1] + " Derosa" print("\nafter:", party_list)

# IndexError Example # [ The variable party_list has only indexes 0, 1, and 2. Therefore, when trying to acess and change # index 3 and error appears because this index doesn't exist in the variable. ] review and run example # which results in an IndexError # if result is NameError run cell above before running this cell # IndexError trying to append to end of list party_list[3] = "Alton" print(party_list)

# [ In this code, the data type of index 3 in the single_digits list is shown by using the # type() method. Then, index 3 is replaced with integer 3 and its type is shown too. ] # review and run example changes the data type of an element # replace a string with a number (int) single_digits = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"] print("single_digits: ", single_digits) print("single_digits[3]: ", single_digits[3], type(single_digits[3]),"\n") # replace string with an int single_digits[3] = 3 print("single_digits: ", single_digits) print("single_digits[3]: ", single_digits[3], type(single_digits[3]))

# [ In this code, the three_num list is defined and its item at index 0 changes depending # on its value. With the if/else statement, we determine what the item at index 0 is # replaced with. If integer is less than 5, it's replaced with the string "small", # but if greater than 5, integer is replaced with string "large". ] complete "replace # items in a list" task three_num = [5, 9, 3] print(three_num) if three_num[0]<5: three_num[0] = "small" else: three_num[0] = "large" print(three_num)

# [ The str_replace() function is defined. It takes 2 arguments: a list and an index. # It replaces the index on the list, which are given as an argument, with a string # depending on its value. The final list is printed.] create challenge function def str_replace(int_list,index): if int_list[index]<5: int_list[index] = "small" else: int_list[index] = "large" print(int_list) str_replace([2,3,8],2)

# [ In this code, 2 items of the variable three_words are modified. The string "Happy" at # index 0 is made uppercase and the string "Rainbow" is swapcased. ] # complete coding task described above three_words = ["Happy","Shoe","Rainbow"] print(three_words) three_words[0] = three_words[0].upper() three_words[2] = three_words[2].swapcase() print(three_words)

# [ The insert() method is similar to the append() method because it adds something to a # list, it doesn't replace. However, with this method you can specify at which index you # want to add the item. In this case, the string "Colette"is added at index 1 and the # other items have to change indexes. ] review and run example # the list before Insert party_list = ["Joana", "Alton", "Tobias"] print("party_list before: ", party_list) print("index 1 is", party_list[1], "\nindex 2 is", party_list[2], "\n") # the list after Insert party_list.insert(1,"Colette") print("party_list after: ", party_list) print("index 1 is", party_list[1], "\nindex 2 is", party_list[2], "\nindex 3 is", party_list[3])

# [ In this case, the insert() method adds an item that is get from user input. A variable # contains the input function and then it's placed in the insert() methd after you # indicated the index. ] insert a name from user input into the party_list in the second # position (index 1) party_list = ["Joana", "Alton", "Tobias"] partyname = input("Enter your name to add you to our party list: ") party_list.insert(1,partyname) # [ The final list is printed ] print the updated list print(party_list)

# [ The error in this code was that the variable tree_list had a string as its value, not a list with # square brackets. To fix this, I added [] to the string "oak". ] Fix the Error tree_list = ["oak"] print("tree_list before =", tree_list) tree_list.insert(1,"pine") print("tree_list after =", tree_list)