Top 15 Virtualenv Interview Questions and Answers

Python job applications can be scary, especially if you don’t know what questions you might be asked during the interview. However, if you prepare well enough, the result can be very rewarding.

And to help you along the way, here are 20 of the most important Python interview questions and how to answer them.

Reading these questions might make you think you won’t be able to answer many of them. But don’t stress. There are courses like GoSkills Intro to Python and Python for Data Analysis that can help you get better at Python.

Virtual environments are an essential tool for Python developers. They allow you to isolate project dependencies and avoid version conflicts.

In job interviews, expect questions about your experience with virtual environments. Being able to explain virtualenv concepts clearly will impress interviewers.

To help you prepare I’ve put together this list of the 15 most common virtualenv interview questions with sample answers

1. What is a Python virtual environment and why is it useful?

A Python virtual environment is an isolated environment for running Python code. It allows you to install Python packages for a specific project without affecting the global Python environment.

Virtualenvs are useful because:

They prevent version conflicts between dependencies of different projects. For example, Project A requires Package X version 1.0 while Project B requires Package X version 2.0. With virtual environments, you can install both versions without conflict.
They allow you to keep dependencies organized per project. You install packages locally inside each virtualenv rather than cluttering up your global site-packages directory.
They enable a clean slate for testing code. You can create disposable virtualenvs to experiment without altering your system.

Overall, virtualenvs enable multiple Python projects to coexist peacefully on the same system. They prevent tricky version and dependency issues.

2. How do you create a virtual environment in Python?

The standard way to create virtual environments is using the venv module in Python’s standard library.

To create a virtualenv with venv:

python -m venv myenv

This will create a myenv directory containing a Python executable and copy of the standard library.

Other common tools for making virtualenvs include:

virtualenv – A third party tool that offers more features like being able to use different Python versions.
conda – Creates virtualenvs managed by the Anaconda Python distribution. Useful for data science.

3. How do you activate and deactivate a virtual environment?

To activate a virtualenv:

On Windows:

myenvScriptsactivate

On Mac/Linux:

source myenv/bin/activate

This will modify PATH and shell variables to use the virtualenv’s Python executable and site-packages directory.

To deactivate the virtualenv later:

deactivate

This resets the shell settings back to normal.

4. What happens when you activate a virtual environment?

Activating a virtualenv modifies 3 important environment variables:

PATH is changed to put the virtualenv’s bin or Scripts directory first. This makes its Python executable available first.
PYTHONHOME is set to the virtualenv’s Python prefix directory. This tells Python where to look for its standard library and settings.
VIRTUAL_ENV is set to the path of the current virtualenv. This allows scripts to detect an active virtualenv.

Additionally, activation scripts can set project-specific variables like DJANGO_SETTINGS_MODULE.

5. How do you install packages inside a Python virtualenv?

To install packages into an activated virtualenv, simply use pip:

pip install <package-name>

This will install the package and all its dependencies into the virtualenv’s site-packages directory rather than the global site-packages.

You can also specify a requirements.txt file for pip to install multiple dependencies:

basic

pip install -r requirements.txt

Updating a virtualenv is as simple as re-running pip install on the packages it contains.

6. What is the difference between virtualenv and venv?

venv is Python’s built-in module for virtual environments. It offers core virtualenv capabilities but minimal customization.

virtualenv is a popular third-party tool that builds on venv:

Customizable activation/deactivation scripts
Support for different Python versions
Bookmarking projects to easily re-create environments
Extensible plugin ecosystem

venv is lightweight and built-in to Python
virtualenv offers richer features and flexibility

For most projects, virtualenv is preferable. But venv is perfectly fine for basic usage.

7. How can you access globally installed packages from inside a virtualenv?

Normally, a virtualenv isolates package installations within its own site-packages directory. But sometimes you may want access to globally installed packages too.

To do this, you can leverage the --system-site-packages option when creating a virtualenv.

For example:

python -m venv myenv --system-site-packages

This will configure the virtualenv to inherit packages from the global Python environment.

So you have access to both global packages and virtualenv-local packages from inside the virtualenv.

8. What is virtualenvwrapper?

Virtualenvwrapper is a set of shell scripts to extend virtualenv usage:

workon switches between different virtualenvs
mkvirtualenv creates new virtualenvs
deactivate to exit the current virtualenv

It also organizes virtualenvs in one location rather than scattered directories.

9. How can you move or copy a virtualenv between machines?

To move or copy a virtualenv between machines, you can simply:

Zip up the entire virtualenv directory
Transfer the zipped folder to the destination machine
Unzip the folder in the desired location

The virtualenv will function identically, provided the destination machine has the same Python version and dependency packages available.

For extra safety, you can use a requirements.txt file to install the virtualenv’s dependencies after copying it over.

10. Can multiple projects share the same virtual environment?

It’s generally best practice for each project to have its own dedicated virtualenv.

However, sometimes teams decide to share a virtualenv between related projects to simplify deployment and avoid duplication.

The main risk of sharing a virtualenv is that updating a dependency for one project could break another. So you lose some isolation.

Overall, use a shared virtualenv only when the projects are tightly coupled and you fully understand the dependency implications. Err on the side of isolation.

11. What are the alternatives to virtualenv in Python?

The major alternatives to virtualenv are:

conda – Anaconda’s virtual environment manager focused on data science.
pipenv – A third-party tool that combines virtualenvs with a pipfile for dependency management.
poetry – Another tool for managing virtualenvs and dependencies via pyproject.toml.
virtualenvwrapper – A wrapper providing convenience functions around virtualenv.

12. How can you configure and distribute a common virtualenv for a team?

For team projects, it can be useful to define a shared virtualenv containing common dependencies.

This shared virtualenv can be configured via:

A requirements.txt file listing dependencies to pip install.
A setup.py file that pip can use to install the virtualenv like a Python package.
A requirements.txt file pip can use to install dependencies on first usage.

The configured virtualenv directory can then be distributed to team members to reuse. Common options include:

Committing the virtualenv folder into source control.
Package and distribute the folder with internal tooling.
Build as an artifact to deploy on infrastructure.

Overall, automating the virtualenv configuration enables consistency across a team.

13. How can you manage multiple virtualenvs on a system?

When working on multiple Python projects, the virtualenv directories can clutter your filesystem.

Some tips for managing multiple virtualenvs:

Use virtualenvwrapper to organize virtualenvs in one location.
Name virtualenvs after their projects so they are easy to identify.
Remove old or unused virtualenvs periodically to clean up.
Use a requirements.txt file to codify the exact dependencies for each virtualenv.
Store project virtualenvs under version control rather than locally.
Use Python dependency management tools like pipenv or poetry.

Overall, a bit of discipline goes a long way to prevent virtualenv sprawl!

14. What is a “seed” file in virtualenv terminology?

A “seed” file gives you a template to auto-generate new virtualenvs without repeating manual configuration.

For example, your team may have a master seed.txt file containing:

Django==2.2.0Pillow==6.2.1

Then a simple command like mkvirtualenv myenv -r seed.txt would create a new virtualenv preinstalled with those packages.

Tell me about Python’s list comprehension feature and give an example of how to use it.

List comprehension is a Python feature that allows you to create lists in a really concise way.

Let’s consider the following example:

We are making a list that has the square of all the numbers from 0 to 999 in this case. But there is a better and quicker way to achieve the same result by using list comprehension:

That’s it, just one line of code.

The basic syntax for a list comprehension is:

You can use the if keyword at the end of the list comprehension like this to say that the expression will only run if a certain condition is met:

Say you only needed the first 1000 squares for odd numbers. You could write your list comprehension like this:

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What is Python’s string slicing feature?

String slicing is a Python feature that makes it easy to find and use parts of a string. A string in Python is an iterable object, which means you can use the slicing feature to find and index single characters, just like you would with any other iterable object.

In order to slice a string, you only need to put the string’s start index and end index in square brackets, with a colon between them.

Say you want to print the first three characters of a string. You can slice it like this:

It’s clear that the Python interpreter treats 0 as the start index if you leave it out.

You will slice the same string from the “P” character to the end of the string in the next example.

Note that in this example, we have omitted the end index. If you leave out the end index, it will be taken as the last index of your iterable object, which in this case is the string.

If you want to show a position starting from the end of the string, you can also use negative indexes, as shown below:

Finally, you can clearly show both the beginning and end indexes. For instance, if you need to get a substring that is in the middle of your input string:

In Python, slicing is a very easy way to change strings, and it works with all iterable objects.

TOP 10 VIRTUAL JOB INTERVIEW TIPS! (How to PASS an Online Zoom, Skype, or HireVue Job Interview!)

FAQ

What is virtualenv used for?

virtualenv is a tool to create isolated Python environments. virtualenv creates a folder which contains all the necessary executables to use the packages that a Python project would need.

What are the benefits of virtualenv?

Virtual environments have many benefits including easier dependency management and reduced risk of package conflicts and errors caused by software deprecation. Software dependency management is the process of bookkeeping software versions needed for a piece of software to run.

What is the difference between venv and virtualenv?

venv is a built-in module in Python 3.3 and later versions that allows you to create isolated Python environments. It is similar to virtualenv , but it is installed by default with Python. pyvenv is a script that comes with Python 3.3 and later versions that allows you to create virtual environments.

Should you ask a virtual interview question?

For some roles, by the time you get to an actual live interview, they’ve already demonstrated the essential skills and the interview is more of a chance to get to know them. You should focus your virtual interview questions more on their personal work style and how you can work best together.

What questions should you ask at a virtual assistant interview?

Here are some basic questions you can expect at the start of your virtual assistant interview: Tell me about yourself. How might your coworkers describe you? How might your current manager describe you? What’s your greatest strength as a virtual assistant? What’s your greatest weakness as a virtual assistant?

How does virtualenv work?

Virtualenv has one basic command: This will create a python virtual environment of the same version as virtualenv, installed into the subdirectory venv. The command line tool has quite a few of flags that modify the tool’s behavior, for a full list make sure to check out CLI flags. The tool works in two phases:

How do I prepare for a virtual interview?

Tailor your responses to the specific job and company, and practice your answers to ensure you shine in your next virtual interview. 1. Tell me about yourself: Context: Interviewers ask this question to assess a candidate’s ability to provide a concise and engaging introduction. It’s an opportunity to create a positive first impression.