python_interview_questions.org

PYTHON INTERVIEW QUESTIONS

Python knowledge is not a must have. However if the candidate claims to have it this might come in handy. Would be nice to have.

Question

*What is the difference between a tuple and a list?*

A tuple is immutable whereas a list is mutable.

Question

*What’s the difference between a variable and an object?*

Variable is a reference to an object, not the object itself.

Question

*What is a dictionary and when might you use one?*

A dictionary is basically a synonym for a hash table.

A collection of key value pairs.

Easier/faster to compute that a list/array. Lookup on a hash table is significantly faster than iterating over a list or array style collection.

Question

*Explain what collection comprehension is?*

A concise way to create a new collection.

List example:

old_list = [1, 3, 5, 26, 28]
new_list = [e for e in old_list if e < 10]
print(new_list) # returns list of elements less than 10

Question

*Explain inheritance and why you would use it?*

A way for new classes to receive the properties and methods of an existing class.

Use for code re-usability.

Question

*What keyword defines a generator function and why would you want to use one?*

yield

Far more memory efficient than normal iterators.

Pipelining potential.

Question

*What are the differences between multi-threading and multiprocessing and when would you use each?*

Multi-threading uses same memory space and it’s therefore affected by the GIL (Global Interpreter Lock).

Multi-processing uses separate memory space and potentially CPU cores.

Multi-threading is better for I/O bound programs and multi-processing is better for CPU bound programs.