Interview Q&A / Python
Python interview questions
Lists, dictionaries, generators, decorators and the Python questions asked in service-company and data roles.
Prefer rapid revision? Practise Python short interview answers →
- What is a generator in Python, and how is yield different from return?
A generator is a function that uses yield to produce values one at a time, pausing after each one and resuming where it left off on the next request. return ends the function and gives back one result, while yield hands out a value and keeps the function's state. Generators save memory because they never build the full list.
IntermediateIn-depth3 min read - How do you read a very large file in Python without loading it all into memory?
Iterate over the file object directly with for line in f. It reads one line at a time through a buffer, so memory use stays small. read() and readlines() load everything at once and can exhaust memory on big files.
IntermediateQuick answer1 min read