Python Data Structures: Dictionaries and Sets Questions and Answers

Question 1

A developer is processing a large log file and needs to store unique IP addresses to count the visitors.
The order of the IP addresses is not important.
Which data structure is the most memory-efficient and performant for this specific task?

Accepted Answer

A set, because it only stores unique elements.

Answer

A list, because it is simple to append to.

Answer

A dictionary, using IP addresses as keys.

Answer

A tuple, because it is immutable.

Question 2

What is a key characteristic of the objects returned by the `.keys()`, `.values()`, and `.items()` methods of a dictionary in Python 3?

Accepted Answer

They are dynamic views that reflect subsequent changes to the dictionary.

Answer

They are static lists containing the dictionary's data at the time of the call.

Answer

They are immutable tuples, preventing any modification.

Answer

They are iterators that are exhausted after a single pass.

Question 3

Which of the following lines of code will result in a `TypeError`?

Accepted Answer

my_dict = {['user', 'id']: 123}

Answer

my_dict = {(1, 2): 'a'}

Answer

my_set = {1, 'hello', 3.14}

Answer

my_set = {frozenset([1, 2]), frozenset([3, 4])}

Question 4

A programmer needs to find elements that are present in `set_A` but NOT in `set_B`. Which set operation should be used?

Accepted Answer

set_A.difference(set_B)

Answer

set_A.union(set_B)

Answer

set_A.intersection(set_B)

Answer

set_A.symmetric_difference(set_B)

Question 5

Consider the following code snippet. What will be the final content of `inventory`?

```python
inventory = {'apples': 10, 'oranges': 5}
updates = {'oranges': 15, 'grapes': 20}
inventory.update(updates)
```

Accepted Answer

{'apples': 10, 'oranges': 15, 'grapes': 20}

Answer

{'apples': 10, 'oranges': 5, 'grapes': 20}

Answer

{'oranges': 15, 'grapes': 20}

Answer

The code will raise a KeyError because 'grapes' is a new key.

Question 6

Which statement correctly describes the fundamental difference between a set and a dictionary?

Accepted Answer

A set stores unique, individual elements, while a dictionary stores key-value pairs.

Answer

Sets are mutable, while dictionaries are immutable.

Answer

A set is an ordered collection, while a dictionary is unordered.

Answer

Sets can only store strings, while dictionaries can store any data type.