{"id":684,"date":"2020-10-21T01:37:29","date_gmt":"2020-10-21T01:37:29","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=684"},"modified":"2025-03-30T09:28:09","modified_gmt":"2025-03-30T09:28:09","slug":"python-virtual-environments","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-virtual-environments\/","title":{"rendered":"Python Virtual Environments"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python virtual environments and how to use the venv<\/code> module to create a virtual environment.<\/p>\n\n\n\n

Why do you need Python virtual environments #<\/a><\/h2>\n\n\n\n

Python stores all system packages in a specified folder when installing Python<\/a>. Typically, most system packages locate at subfolders of a path specified in the sys.prefix<\/code>. To find this path, you can import the sys<\/code> module and display it as follows:<\/p>\n\n\n

import<\/span> sys\n\nprint(sys.prefix)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
It’ll show something like this on Windows:<\/p>\n\n\n
C:\\python<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
import<\/span> site\nprint(site.getsitepackages())<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
It returns something like this on Windows:<\/p>\n\n\n
['C:\\\\python'<\/span>, 'C:\\\\python\\\\Lib\\\\site-packages'<\/span>]<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
You’ll be fine if you have some projects that use only standard Python libraries. However, it’ll be a problem when you have some projects that use third-party packages.<\/p>\n\n\n\n
Suppose you have two projects that use different versions of a library. Since there is only one location to store the third-party packages, you cannot keep different versions at the same time.<\/p>\n\n\n\n
This is where virtual environments come into play.<\/p>\n\n\n\n
What is a Python virtual environment #<\/a><\/h2>\n\n\n\n
Python uses virtual environments<\/strong> to create an isolated environment<\/strong> for every project. In other words, each project will have its own directory to store third-party packages.<\/p>\n\n\n\n
In case you have multiple projects that use different versions of a package, you can store them in separate virtual environments.<\/p>\n\n\n\n
Python includes the virtual environment module (venv<\/code>) as a standard library since version 3.3. Therefore, to use the venv<\/code> module, you should have Python 3.3 or later.<\/p>\n\n\n\n
To check the Python’s version, you can use the following command:<\/p>\n\n\n
python --version<\/code><\/span><\/pre>\n\n\n
Using the venv module to create a virtual environment #<\/a><\/h2>\n\n\n\n
The following example shows you how to create a new project on Windows, which uses a virtual environment created by the venv<\/code> built-in module.<\/p>\n\n\n\n
First, create a new folder for hosting the project and virtual environment:<\/p>\n\n\n
mkdir D:\\test_env\ncd test_env<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, create a virtual environment with the name .venv<\/code> inside the test_env<\/code> folder:<\/p>\n\n\n
python -m venv .venv<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The above command will create a new folder called .venv<\/code> with all necessary tools and libraries for running Python programs.<\/p>\n\n\n\n
Second, activate the virtual environment by running the activate.bat file in the project_env\/Scripts<\/code> directory:<\/p>\n\n\n
.venv\\Scripts\\activate<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Once executed, you’ll see the following in the terminal:<\/p>\n\n\n
(.venv) D:\\test_env><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The prefix (.venv<\/code>) indicates that you’re in the .venv<\/code> virtual environment.<\/p>\n\n\n\n
Now, you can check where the python.exe<\/code> is located:<\/p>\n\n\n
where python<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
This time it returns the following paths:<\/p>\n\n\n
D:\\test_env\\.venv\\Scripts\\python.exe\nC:\\python\\python.exe\nC:\\Users\\<username>\\AppData\\Local\\Microsoft\\WindowsApps\\python.exe<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The first line shows that the python.exe<\/code> is located in the .venv\/Scripts<\/code> folder. It means that if you run the python command within the test_env<\/code>, the D:\\test_env\\.env\\Scripts\\python.exe<\/code> will execute instead of C:\\python\\python.exe<\/code>.<\/p>\n\n\n\n
Third, show the packages installed in the .venv<\/code> virtual environment for the test_env<\/code> project:<\/p>\n\n\n
pip list<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Package Version\n------- -------\npip     24.3<\/span>.1<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
When you created the .venv<\/code> virtual environment, the venv<\/code> module already installed the package  pip<\/code>.<\/p>\n\n\n\n
Fourth, install the requests<\/code> package in the virtual environment:<\/p>\n\n\n
pip install requests<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If you display all packages installed in the .venv<\/code> virtual environment:<\/p>\n\n\n
pip list<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
you’ll see the requests<\/code> package and its dependencies:<\/p>\n\n\n
Package            Version\n------------------ ---------\ncertifi            2025.1<\/span>.31<\/span>\ncharset-normalizer 3.4<\/span>.1<\/span>\nidna               3.10<\/span>\npip                24.3<\/span>.1<\/span>\nrequests           2.32<\/span>.3<\/span>\nurllib3            2.3<\/span>.0<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Fifth, create the requirements.txt<\/code> file:<\/p>\n\n\n
pip freeze > requirements.txt<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The content of the requirements.txt<\/code> will look like this:<\/p>\n\n\n
certifi==2025.1<\/span>.31<\/span>\ncharset-normalizer==3.4<\/span>.1<\/span>\nidna==3.10<\/span>\nrequests==2.32<\/span>.3<\/span>\nurllib3==2.3<\/span>.0<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The requirements.txt<\/code> file contains all the packages with versions installed in the .venv<\/code> virtual environment used for the project.<\/p>\n\n\n\n
When you copy the project to a different machine, you can run the pip install<\/code> command to install all the packages listed in the requirements.txt<\/code> file using the following command:<\/p>\n\n\n
pip<\/span> install<\/span> -r<\/span> requirements<\/span>.txt<\/span><\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
Sixth, create the main.py<\/code> file that uses the requests<\/code> module:<\/p>\n\n\n
import<\/span> requests\n\nresponse = requests.get('https:\/\/www.google.com'<\/span>)\nif<\/span> response.status_code == 200<\/span>:\n    print(response.text)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
To run the main.py<\/code> file, you can use the python<\/code> command:<\/p>\n\n\n
python main.py<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
This command executes the python.exe<\/code> from the .venv<\/code><\/code> and loads the packages installed in the .venv<\/code><\/code> virtual environment.<\/p>\n\n\n\n
To deactivate the virtual environment, you can run the deactivate<\/code> command:<\/p>\n\n\n
deactivate<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
It’ll return the following:<\/p>\n\n\n
D:\\test_env><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Now, you don’t see the (.venv<\/code><\/code>) prefix anymore. It means that you’re not in the .venv<\/code><\/code> virtual environment.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
A workaround is that you can use the pip<\/a><\/code> command to switch between versions by installing\/uninstalling the packages. However, it will be time-consuming and not scale very well.<\/p>\n\n\n\n
When you use pip<\/a> to install third-party packages, Python stores these packages in a different folder specified by the site.getsitepackges()<\/code> function:<\/p>\n\n\n