Sets, Tuples, Dictionary

Which statement correctly describes a Python set?

• Elements within a set must be mutable types.

• Sets are mutable, allowing additions and removals of elements.

• A set is an ordered collection of unique items

• Sets allow duplicate elements.

Answer explanation

A set is an unordered collection of unique items.

Elements within a set must be immutable types.

Sets does not allow duplicate elements.

How do you add a single element to a Python set named `my_set`?

• Using `my_set[index] = element`

• Using `my_set.insert(element)`

• Using `my_set.append(element)`

• Using `my_set.add(element)`

Which set operation in Python returns a new set containing all unique elements from both sets?

• set1.union(set2)

• set1.difference(set2)

• set1.symmetric_difference(set2)

• set1.intersection(set2)

When would you typically use a Python set instead of a list?

• To maintain the order of elements for fast retrieval.

• To maintain the order of elements for fast retrieval.

• To store a collection of unique items where order does not matter.

• To store key-value pairs.

Answer explanation

Sets are ideal for membership testing and eliminating duplicates because they only store unique, unordered elements.

How do you add a new key-value pair to a Python dictionary named `my_dict`?

• my_dict.add(key, value)

• my_dict.append(key, value)

• my_dict.insert(key, value)

• my_dict[key] = value

In what scenario would you prefer using a tuple over a list in Python?

• When you need to map keys to values.

• When you need an ordered collection of items that should not change.

• When you need a collection where elements can be modified frequently.

• When you need to store unique items and perform set operations.

Which characteristic is true about Python dictionaries?

• Values must be unique.

• Keys can be any mutable type.

• They are accessed by index.

• They are ordered collections of key-value pairs.

Answer explanation

Dictionaries are accessed by their keys, not by numerical indices.

Keys can be only immutable type.

Values may not be unique within a dictionary, but keys are.

Which statement is true about Python tuples?

• They are used for storing key-value pairs.

• They are ordered collections, and elements can be accessed by index.

• They are mutable, allowing elements to be changed after creation.

• They are defined using curly braces `{}`.

Answer explanation

No, tuples are not primarily designed for storing key-value pairs. Tuples are ordered collections of items, while dictionaries are data structures specifically designed to store key-value pairs. However, tuples can be used as keys in dictionaries because they are immutable and hashable, meaning they can be uniquely identified. Dictionaries can also return key-value pairs as a list of tuples. 

They are immutable, not allowing elements to be changed after creation.

They are defined using round braces `()`.

How can you safely retrieve a value from a dictionary `my_dict` for a key 'age', returning 0 if the key is not found?

• my_dict.get('age', 0)

• my_dict.find('age')

• my_dict['age']

• my_dict.lookup('age', 0)

How do you remove a specific key-value pair from a Python dictionary named `my_dict` given the key `key_to_remove`?

• my_dict.pop_item('key_to_remove')

• my_dict.remove('key_to_remove')

• del my_dict['key_to_remove']

• my_dict.delete('key_to_remove')