Python Data Structures: Dictionaries and Sets 5

Question 1

What does `set.issubset()` return when called as `{1, 2}.issubset({1, 2, 3})`?

Accepted Answer

True

Answer

`issubset()` returns True if every element of the calling set is also in the argument set.

Question 2

What is the output of `d = {'a': [1, 2]}; e = d.copy(); e['a'].append(3); print(d['a'])`?

Accepted Answer

[1, 2, 3]

Answer

`dict.copy()` performs a shallow copy, so the list value is shared between `d` and `e`; mutating it through `e` also affects `d`.

Question 3

Which method removes ALL elements from a set without deleting the set object?

Accepted Answer

.clear()

Answer

`set.clear()` removes all elements in place, leaving an empty set object.

Question 4

What is the output of `{x**2 for x in range(4)}`?

Accepted Answer

{0, 1, 4, 9}

Answer

Curly braces with a single expression (no colon) and a `for` clause create a set comprehension.

Question 5

What does `{1, 2, 3}.isdisjoint({4, 5, 6})` return?

Accepted Answer

True

Answer

`isdisjoint()` returns True when two sets share no common elements.

Python Practice Test