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Python interview questions

2 November 2023 , by Josh Nel

When scaling your team, finding the right Python developer can be a challenge. A poor hiring decision can lead to setbacks, low-quality code, and wasted time. Here, we look at Python interview questions you can use to find the perfect technical and cultural fit for your team.

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Questions to ask when interviewing a Python developer

Before diving into the technical details, it can be helpful to start with a few questions to assess a candidate’s approach to technical problems, their knowledge of the latest ecosystem developments, and how they might collaborate with your team. Here are a few questions you can use in your next interview:

  • Can you describe a challenging Python project you've worked on and the solutions you implemented to overcome the challenges?
  • How do you stay up to date with the latest Python developments and best practices?
  • Describe a situation where you had to optimise Python code for performance. What techniques did you use, and what was the outcome?
  • How do you approach debugging in Python when you encounter an issue in your code?
  • Can you give an example of a time when you had to collaborate with team members on a Python project? How did you ensure effective communication and teamwork?
  • What is your preferred Python development environment, and can you explain why you like it?
  • Have you worked with any Python web frameworks (e.g., Django, or Flask)? If so, can you discuss your experience and projects related to them?
  • Can you provide an example of a challenging Python problem you encountered and how you approached solving it?

Python technical interview questions

Now that you’ve covered a few behavioural questions, you can move on to assessing a candidate's technical ability. Here, we’ll look at some general interview questions, plus a few specific questions for Python developers at different levels of seniority.

Some general technical questions for Python developers include:

  • What is PEP 8, and why is it important?
  • Can you explain the Global Interpreter Lock (GIL) in Python and its implications for multi-threading?
  • What is the difference between Python 2 and Python 3, and what version should you use for new projects?
  • Explain the differences between lists, tuples, and sets in Python.
  • How does Python's garbage collection work, and why is it important?
  • Describe decorators in Python and provide an example of their use.
  • Explain the concept of Python virtual environments and why they are useful.
  • How do you handle exceptions and errors in Python, and what is the purpose of the try, except, and finally blocks?
  • Can you explain the difference between "deep copy" and "shallow copy" in Python?
  • What are list comprehensions, and why are they preferred over traditional for-loops in Python?

If you’re interviewing for junior or intermediate Python developers, consider including a few of these questions:

  • Explain the differences between Python 2 and Python 3. Why should new projects use Python 3?
  • How do you comment on a single-line and a multi-line block of code in Python?
  • Describe the purpose of Python's zip() function and provide an example of its usage.
  • What is the difference between append() and extend() methods for lists in Python?
  • Explain the concepts of pass by value and pass by reference in Python. How are function arguments passed?
  • Discuss the concept of variable scope in Python. What is the difference between local and global variables?
  • How do you open and close files in Python, and why is it important to close them?

For more senior Python developers, more advanced questions might be appropriate:

  • What are decorators in Python? Provide an example of a custom decorator function.
  • Explain the Global Interpreter Lock (GIL) in Python and its implications for multi-threading.
  • How can you use generators and iterators in Python to efficiently work with large data sets?
  • Describe the use of context managers in Python and provide an example.
  • How can you implement a singleton pattern in Python?

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