This cheat sheet provides explanations, examples, and solutions to fundamental and intermediate Python topics, along with practical interview questions and use cases. It is designed to help beginners and professionals quickly grasp the concepts and ace coding interviews.
What it tests: Understanding of Python’s internals, especially when handling large datasets.
Answer:
Python uses reference counting and a cyclic garbage collector. Objects are cleaned up once their reference count drops to zero. For cyclic references, the garbage collector periodically looks for unreachable objects. This is critical in long-running or memory-intensive data jobs to avoid leaks or crashes.
Follow-up:
How do you manually trigger garbage collection or release memory?
Use del, gc.collect(), or process large data in batches to avoid holding everything in memory.
is and == in Python, and how can it impact data comparison?What it tests: Object identity vs value comparison—important in debugging transformations.
Answer:
is checks if two variables point to the same object in memory, while == checks if their values are equal. In data workflows (e.g., Pandas), using is instead of == can lead to unexpected comparison results and logic errors.
What it tests: Knowledge of Python function behavior and scope.
Answer: