PyPi and Pip

Learning Goals

• Installing packages using pip.

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Key Vocab

• Module: a file containing Python definitions and statements. A module's functions, classes, and global variables can be accessed by other modules.
• Package: a collection of modules that can be accessed as a group using the package name.
• import: the Python keyword used to access data from other packages and modules inside of the current module.
• PyPI: the Python Package Index. A repository of Python packages that can be downloaded and made available to your application.
• pip: the command line tool used to download packages from PyPI. pip is installed on your computer automatically when you download Python.
• Virtual Environment: a collection of modules, packages, and scripts that can be activated or deactivated at any time.
• Pipenv: a virtual environment tool that uses pip to manage the modules, packages, and scripts that you intend to use in your application.

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Introduction

Package Installer for Python (Pip) is the default package manager for python and is used to install and manage software packages. It uses an online repository called Python Package Index (PyPi).

We can search PyPi for libraries using the search bar on the site.

Installing Packages using Pip

We can use the Pip command to install python packages from the Python Package Index (PyPi). Lets practice this using a package called requests. Requests is a HTTP library for the Python programming language.

pip install requests

Now we have access to the requests module. It can be imported in our python programs.

$ python
>>> import requests

To install a specific version of the module we can use pip install

pip install requests==2.22.0

Requirements files are files containing a list of modules to be installed using pip install.

pip install -r requirements.txt

Constraints files are requirements files that only control which version of a requirement is installed, not whether it is installed or not.

pip install -c constraints.txt

Example of a requirements.txt or constraints.txt file.

requests==2.28.1
uvicorn==0.18.2
fastapi==0.79.0

To uninstall a package

pip uninstall requests

Conclusion

Pip can be used to install packages from the Python Package Index. It gives us access to many libraries to help us develop.

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Resources

• Python 3 Documentation
• pip
• PyPi