PCEP Computer Programming and Python Fundamentals Practice Question

A company is developing a data processing pipeline that must handle large datasets efficiently. They notice that using a list comprehension to filter data is slower than expected. Which alternative approach would likely improve performance?

⚠ Common exam trap

The PCEP exam often tests the misconception that map() or lambda functions are inherently faster for filtering, when in fact the key performance difference lies in lazy evaluation versus eager list construction, which is the core advantage of generator expressions.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Using a generator expression

Generator expressions produce items lazily, one at a time, without storing the entire filtered result in memory. This reduces memory overhead and can improve performance when processing large datasets, as the pipeline can iterate over generated items without building a full list first.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Using the map() function
Why it's wrong here
map() returns an iterator, but it still processes all elements; for filtering, a generator expression is more direct.
✗
Using a for loop with append
Why it's wrong here
A for loop with append creates a list as well, so similar performance.
✓
Using a generator expression
Why this is correct
Generators yield items one by one and avoid storing the entire list, reducing memory and often improving speed.
✗
Using a lambda function
Why it's wrong here
Lambda is not an alternative to list comprehension; it's a way to create anonymous functions.

Go deeper

PCEP Computer Programming and Python Fundamentals Practice Question

Why each option matters

Option-by-option breakdown

Related to this question