Python Data Structures & Algorithms Flashcards

What is the purpose of the `__init__` method in a Python class?

Answer: To initialize the attributes of a new object when it is created

The __init__ method is the constructor that runs automatically when a new instance of a class is created, allowing you to set initial values for the object's attributes.

What does the `lambda` keyword create in Python?

Answer: An anonymous (unnamed) function defined in a single expression

Lambda creates a small anonymous function that can take any number of arguments but can only contain a single expression. It is often used with functions like map(), filter(), and sorted().

What is the output of: print(type({}))?

Answer:

Empty curly braces {} create an empty dictionary in Python, not an empty set. To create an empty set, you must use set(). This is a common Python gotcha.

Which method would you use to remove and return the last element from a Python list?

Answer: pop()

The pop() method without arguments removes and returns the last element of a list. With an index argument, it removes and returns the element at that position.

What is a Python generator and how does it differ from a regular function?

Answer: A function that uses yield to produce a sequence of values lazily, one at a time

Generators use the yield keyword to produce values one at a time on demand (lazy evaluation), saving memory compared to creating an entire list. They maintain state between yields.

What does the `*args` parameter allow in a Python function definition?

Answer: Accepting a variable number of positional arguments as a tuple

*args collects any number of positional arguments into a tuple, allowing the function to be called with varying numbers of arguments. Similarly, **kwargs collects keyword arguments into a dictionary.