Python (ME-506) - Important Questions

Explain different ways of passing arguments to a Python function. Discuss positional arguments, keyword arguments, default arguments, variable-length arguments using *args and **kwargs, and keyword-only arguments. Illustrate each case with a concise code example.

Write two Python functions to compute the factorial of a non-negative integer $n$: one using recursion and one using an iterative loop. Compare their time and space complexity and state which version would be preferred for large $n$ and why.

Explain the concepts of closure and decorator in Python. Write a decorator called timeit that measures and prints the execution time of the decorated function. Demonstrate its use on a sample function.

What is the difference between an iterator and a generator in Python? Implement a generator function that yields the Fibonacci sequence up to the $n$-th term. Discuss the memory advantage of using a generator compared to returning a list.

Describe how to create a Python package. Explain the role of init.py, and demonstrate how to structure a package with two modules so that one module can import the other. Explain absolute versus relative imports with examples.

Write Python code to perform the following tasks: (a) Open a text file and read it line by line, printing each line with its line number. (b) Write a list of dictionaries to a file in JSON format. (c) Explain how binary file I/O differs from text I/O and give an example of writing and reading binary data.

Explain Python's exception handling mechanism using try, except, else, and finally. Define a custom exception class called InvalidAgeError and write a function validate_age(age) that raises this exception when the age is negative or unreasonably large.

Compare JSON serialization and pickle in Python. Give a code example that demonstrates how to serialize and deserialize a custom Python object to JSON by providing a custom encoder/decoder or by converting the object to and from a dictionary.

Explain the use of the re module functions compile, search, match, and findall. Write a regular expression to validate a simple email address and use it to extract the username and domain parts for the input string.

Explain lambda expressions in Python. Using lambda, map, filter, and reduce (from functools), write code to compute the sum of squares of even numbers from a given list of integers. Also show an equivalent solution using list comprehensions.

Write a unit test using the unittest framework for a function is_prime(n) that returns True if $n$ is prime. Also explain how doctest can be used to test small functions and show a simple doctest example inside a function's docstring.

Describe how to parse command-line arguments in Python using the argparse module. Write a short script that accepts a filename and a verbosity flag (--verbose) and prints appropriate messages based on the flag.