Week 4 Practice

Concepts Reviewed

These questions are optional supplements that ideally help you get prepared for the quizzes ahead of time. (Some of them are also designed for elaboration purposes as you can see from the tag. Don’t worry them if you just want to get prepared for the quizzes) Before working through these practice questions, you should get familiar with the concepts covered in the lessons of the fourth week.


Questions

These questions might not be in the same format as quizzes. Don’t hesitate to bring them to the Tutoring section for help.

Lists

  1. What happens when you assign one list to another (e.g., list1 = list2) and then modify one of the lists? Say we now modify the values of list 2, will the values of list 1 also get changed?

list1 = [1, 2, 3, 4]
list2 = list1
list2.append(5)
print(list1)

Considering the above codes, what would be printed out as the output? A) [1, 2, 3, 4, 5] B) [1, 2, 3, 4] C) [5, 4, 3, 2, 1] D) Error

  1. Where should we put a newly created list in the Memory Diagram?

  2. Recall the Chapter when we learn String, how to use the index to access the last item within a list without calling the function len()?

  3. Function writing relates to the list: 5.1 Could you write a function that will take a list of int and return the average of this list of int?

  4. Identify the usage and difference of pop() and append() in list.

  5. (For elaboration)In Python, which method can be used to combine two lists into a single list?

  1. combine()
  2. append()
  3. extend()
  4. join()

  1. (For elaboration)Identify the following statements regarding list slicing are True or False: 8.1 list[::2] returns items at even indices only. 8.2 list[::-1] reverses the list. 8.3 list[1:3] returns the first three items. 8.4 list[:3] returns the last three items.

a = [1, 2, 3]
b = a * 2
b[0] = 5
print(a)
print(b)

Considering the above codes, what would be the outputs of the last two print() functions?

  1. Say I have a new item that, instead of adding it to the end of the list, but at the specific index. Which built-in function would be the correct one to use for this purpose?

  2. Identify the following statements are True or False:

11.1 Lists can contain elements of different data types. 11.2 Lists are mutable. 11.3 The + operator can be used to append elements to a list. 11.4 Lists can be nested within other lists.

my_list = ['Python', 'is', 'awesome', 'is', '110', 'is', 'cool']

Write a one-line code that can return the index of 110 in this list.

  1. Continue on 12:
print(my_list.index('is'))

What would be the output of this line of code based on the my_list from Q12? A) 1 B) 2 C) 3 D) [1, 3]

Solutions

Lists

  1. Yes, it will get changed. In Python, a list is a reference data type. So assigning list1 = list2 means they are now referring to the same list.

  2. A

  3. Heap

  4. list[-1]

  5. The append() method adds a single element to the end of the list. Whereas the pop() method removes and returns the last element of the list. If an index is given, it removes and returns the element at that index.

  6. C

  7. 8.1 True 8.2 True 8.3 False 8.4 False

  8. [1, 2, 3] and [5, 2, 3, 1, 2, 3]

  9. .insert()

  10. 11.1 True 11.2 True 11.3 False 11.4 True

  11. print(my_list.index(‘110’))

  12. A

Contributor(s): Vincent Li