Packages and virtual environments#
PIP is a package manager for Python for packages or modules
Create and start the virtual environment#
Since Python 3.3, you can create and start a virtual environment as the venv module is now part of the standard library. We will use the venv module to create a virtual environment in the current directory.
1 $ python3 -m venv .venv
2 $
In the bin directory of the virtual environment, there is a file called activate. This file contains the command to activate the virtual environment with the Bash or Zsh shell.
1 $ source .venv/bin/activate
2 (.venv) $ python
3 Python 3.9.2 (default, Feb 20 2021, 00:00:00)
4 [GCC 10.2.1 20201125 (Red Hat 10.2.1-9)] on linux
5 Type "help", "copyright", "credits" or "license" for more information.
6 >>> import sys
7 >>> sys.path
8 ['', '/usr/lib64/python39.zip', '/usr/lib64/python3.9', '/usr/lib64/python3.9/lib-dynload', '/workspaces/python-examples/.venv/lib64/python3.9/site-packages', '/workspaces/python-examples/.venv/lib/python3.9/site-packages']
9 >>>
Managing packages with pip#
Since Python 3.4 the pip package is part of the standard library and can be called as a module or as an executable.
Example:
1 $ source .venv/bin/activate
2 (.venv) $ python -m pip search camelcase
3 (.venv) $ pip search camelcase
Note
The pip package can only be upgraded when it is called as a module.
Warning
Since late 2020 the search functionality of the pip package has been deprecated due to performance issues on PyPi infrastructure.
Example:
1 (.venv) $ pip install camelcase
2 Collecting camelcase
3 Using cached camelcase-0.2.tar.gz (1.3 kB)
4 Using legacy 'setup.py install' for camelcase, since package 'wheel' is not installed.
5 Installing collected packages: camelcase
6 Running setup.py install for camelcase ... done
7 Successfully installed camelcase-0.2
Example:
1 (.venv) $ pip install camelcase==0.1
2 Collecting camelcase==0.1
3 Downloading camelcase-0.1.tar.gz (1.2 kB)
4 Using legacy 'setup.py install' for camelcase, since package 'wheel' is not installed.
5 Installing collected packages: camelcase
6 Attempting uninstall: camelcase
7 Found existing installation: camelcase 0.2
8 Uninstalling camelcase-0.2:
9 Successfully uninstalled camelcase-0.2
10 Running setup.py install for camelcase ... done
11 Successfully installed camelcase-0.1
Example:
1 (.venv) $ pip install --upgrade camelcase
2 Collecting camelcase
3 Using cached camelcase-0.2.tar.gz (1.3 kB)
4 Using legacy 'setup.py install' for camelcase, since package 'wheel' is not installed.
5 Installing collected packages: camelcase
6 Attempting uninstall: camelcase
7 Found existing installation: camelcase 0.1
8 Uninstalling camelcase-0.1:
9 Successfully uninstalled camelcase-0.1
10 Running setup.py install for camelcase ... done
11 Successfully installed camelcase-0.2
Example:
1 (.venv) $ pip show camelcase
2 Name: camelcase
3 Version: 0.2
4 Summary: Converts a string to Camel Case
5 Home-page: http://www.craigaddyman.com
6 Author: Craig Addyman
7 Author-email: [email protected]
8 License: MIT
9 Location: /workspaces/mastering-python/.venv/lib/python3.9/site-packages
10 Requires:
11 Required-by:
Output:
1 (.venv) $ pip list
2 Package Version
3 ---------- -------
4 camelcase 0.2
5 pip 20.2.2
6 setuptools 49.1.3
Install all dependencies#
Example:
1 (.venv) $ pip freeze > requirements.txt
2 (.venv) $ cat requirements.txt
3 camelcase==0.2
Example:
1 (.venv) $ pip uninstall camelcase
2 Found existing installation: camelcase 0.2
3 Uninstalling camelcase-0.2:
4 Would remove:
5 /workspaces/mastering-python/.venv/lib/python3.9/site-packages/camelcase-0.2-py3.9.egg-info
6 /workspaces/mastering-python/.venv/lib/python3.9/site-packages/camelcase/*
7 Proceed (y/n)? y
8 Successfully uninstalled camelcase-0.2
Example:
1 (.venv) $ pip install -r requirements.txt
2 Collecting camelcase==0.2
3 Using cached camelcase-0.2.tar.gz (1.3 kB)
4 Using legacy 'setup.py install' for camelcase, since package 'wheel' is not installed.
5 Installing collected packages: camelcase
6 Running setup.py install for camelcase ... done
7 Successfully installed camelcase-0.2