PCEP Certification Practice Test: List Comprehensions

Question 1: Which of the following correctly uses list comprehension to create a list of squares for the numbers 1 through 5?

1. [x ** 2 for x in range(1, 6)]
2. [x ** 2 for x in range(5)]
3. [x * 2 for x in range(1, 5)]
4. [x for x in range(1, 6)]

Question 2: What is the output of the following code?

numbers = [1, 2, 3, 4]
squares = [x * x for x in numbers]
print(squares)

1. [1, 2, 3, 4]
2. [1, 4, 9, 16]
3. [2, 4, 6, 8]
4. [1, 2, 3, 4, 5]

Question 3: Which of the following list comprehensions creates a list of even numbers from 0 to 10?

1. [x for x in range(11) if x % 2 == 0]
2. [x for x in range(11) if x % 2 == 1]
3. [x for x in range(10) if x % 2 == 0]
4. [x for x in range(12) if x % 3 == 0]

Question 4: Which of the following list comprehensions generate a list of squares for numbers from 1 to 3? (Choose two)

1. [x ** 2 for x in range(1, 4)]
2. [x ** 2 for x in range(3)]
3. [x * x for x in range(1, 4)]
4. [x for x in range(1, 4)]

Question 5: Which of the following statements about list comprehensions are correct? (Choose all that apply)

1. List comprehensions are used to create new lists based on existing iterables.
2. List comprehensions can include conditional statements.
3. List comprehensions cannot be nested.
4. List comprehensions always result in a list with the same length as the original iterable.

Question 6: The expression [x * 2 for x in range(5)] generates a list of __________.

Question 7: List comprehensions can include conditions using the __________ keyword to filter elements.

Question 8: Arrange the following code statements in the correct order to create a list comprehension that filters only positive numbers from a list:

1. numbers = [-5, -3, 0, 2, 4]
2. positive_numbers = [x for x in numbers if x > 0]
3. print(positive_numbers)

Question 9: Arrange the following code snippets in the correct order to generate a list of even numbers from 1 to 10 using list comprehension:

1. print(evens)
2. [x for x in range(1, 11) if x % 2 == 0]
3. evens =

Question 10: Complete the code to create a list comprehension that doubles the numbers in the list numbers:

numbers = [1, 2, 3, 4]
doubled = [__________]

Question 11: Complete the code to generate a list of numbers from 1 to 10 that are divisible by 3:

multiples_of_three = [__________]
print(multiples_of_three)

Question 12: Insert the correct code to create a list comprehension that converts all strings in the list words to uppercase:

words = ["hello", "world"]
uppercase_words = __________

Question 13: Insert the correct code to generate a list of squares for even numbers from 1 to 10:

squares = __________

Question 14: Rearrange the code to create a list comprehension that filters only the numbers greater than 10 from a list:

1. if x > 10]
2. [x for x in numbers
3. numbers = [5, 12, 8, 20, 15]

Question 15: Organize the steps to generate a list comprehension that extracts the first letter of each word in the list:

1. first_letters = [word[0] for word in words]
2. print(first_letters)
3. words = ["apple", "banana", "cherry"]

Question 16: What does the following code output?

numbers = [1, 2, 3, 4, 5]
result = [x * 3 for x in numbers]
print(result)

1. [1, 2, 3, 4, 5]
2. [3, 6, 9, 12, 15]
3. [2, 4, 6, 8, 10]
4. None

Question 17: What does the following code output?

words = ["apple", "banana", "cherry"]
lengths = [len(word) for word in words]
print(lengths)

1. [5, 6, 6]
2. [5, 7, 6]
3. [5, 7, 7]
4. [5, 6, 7]

Question 18: List comprehensions can only be used with numbers.

1. True
2. False

Question 19: A list comprehension can include both an if and else condition.

1. True
2. False

Question 20: What happens if you use list comprehension on an empty list?

1. It raises an error
2. It returns an empty list
3. It returns None
4. It returns a list of None values

Question 21: Which of the following statements about list comprehensions is correct?

1. List comprehensions must always include a conditional statement.
2. List comprehensions can be nested within each other.
3. List comprehensions cannot perform operations on elements.
4. List comprehensions can only be used with numerical data.

Question 22: Which of the following expressions would correctly generate a list of the first 10 multiples of 3?

1. [x * 3 for x in range(10)]
2. [x * 3 for x in range(1, 11)]
3. [x * 3 for x in range(3, 30)]
4. [x + 3 for x in range(1, 11)]

Question 23: List comprehensions provide a concise way to __________ elements from an existing iterable.

Question 24: The structure of a basic list comprehension is [expression for item in __________].

Question 25: What is the output of the following code?

nums = [2, 4, 6, 8]
result = [x - 1 for x in nums]
print(result)

1. [1, 3, 5, 7]
2. [2, 4, 6, 8]
3. [3, 5, 7, 9]
4. [1, 2, 3, 4]