Lists, two-dimensional lists and records

Overview

Python lists as arrays, append, insert and del, two-dimensional lists, records as lists of fields, and worked loops over lists of lists.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   How is an array represented in Python?

   Model answer

   Python represents an array as a list, such as scores = [12, 15, 9]. Each item is reached by an index that starts at 0.

2. 2

   What is printed by scores = [12, 15, 9, 20], then print(scores[2])?

   Model answer

   The code prints 9. Index 2 is the third item because indexes start at 0.

3. 3

   What does scores.append(7) do when scores = [12, 15, 9]?

   Model answer

   The list becomes [12, 15, 9, 7]. The append() method adds the item to the end.

4. 4

   What is the list after names = ["Ann", "Bo", "Cy"], then del names[1]?

   Model answer

   The list becomes ["Ann", "Cy"]. The del statement removes the item at index 1.

5. 5

   Give the list after nums = [4, 8, 12], then nums.insert(1, 6).

   Model answer

   The list becomes [4, 6, 8, 12]. The insert() method places 6 just before the item at index 1.

6. 6

   What is printed by print(len([3, 6, 9, 12, 15]))?

   Model answer

   The code prints 5. The len() function counts the items in the list.

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