List Comprehension Examples in Python for High School Data Science

📚 Quick Study Guide

• 💡 Definition: List comprehension provides a concise way to create lists in Python. It's a shorthand for loops and conditional statements.
• 📝 Basic Syntax: `[expression for item in iterable if condition == True]`
• 🔢 Example: Squaring numbers from 0 to 9: `[x2 for x in range(10)]`
• 🧪 Conditional Logic: You can include `if` statements to filter elements.
• ⏱️ Benefits: More readable and often faster than traditional loops.
• 💻 Use Cases: Data cleaning, transformation, and feature engineering.
• 🧠 Nested List Comprehensions: Create lists of lists using nested loops within the comprehension.

1. What is the output of the following code?

   [x for x in range(5)]

   1. [0, 1, 2, 3, 4]
   2. [1, 2, 3, 4, 5]
   3. [0, 2, 4]
   4. [1, 3, 5]

2. Which of the following is the correct syntax for a list comprehension?

   1. (expression for item in iterable)
   2. {expression for item in iterable}
   3. [expression in item for iterable]
   4. [expression for item in iterable]

3. What will be the output of this code?

   [x*2 for x in range(5) if x % 2 == 0]

   1. [0, 1, 2, 3, 4]
   2. [0, 2, 4, 6, 8]
   3. [0, 4, 8]
   4. [2, 6]

4. What does 'iterable' represent in a list comprehension?

   1. A condition to filter elements.
   2. A sequence (like a list or range) to iterate over.
   3. An expression to be evaluated.
   4. A function to apply to each element.

5. Which of the following list comprehensions squares only the odd numbers in the range 0-9?

   1. [x2 for x in range(10)]
   2. [x for x in range(10) if x % 2 != 0]
   3. [x2 for x in range(10) if x % 2 == 0]
   4. [x2 for x in range(10) if x % 2 != 0]

6. What is the primary benefit of using list comprehension over traditional loops?

   1. Increased code complexity
   2. Improved readability and conciseness
   3. Reduced memory usage
   4. Enhanced debugging capabilities

7. What will the following code output?

   [ (x, y) for x in [1,2,3] for y in [4,5,6]]

   1. [(1, 4), (2, 5), (3, 6)]
   2. [(1, 2, 3), (4, 5, 6)]
   3. [(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)]
   4. Error