Are you ready to learn about Python packaging? It might seem like an afterthought at first glance, but it’s actually essential for making your code accessible and usable by others. In this article, we’ll talk about how to read metadata in Python packages using pip the official package manager for Python.
First: what is metadata? It refers to information about a package that isn’t part of its actual code. This includes details like version numbers, author names, license details, and installation instructions. Getting this stuff right can make all the difference in terms of user adoption and community support.
So how do we access metadata using pip? Let’s say you have a package installed locally (i.e., in your current working directory). To retrieve its metadata, simply import it directly into your script or console session:
# Importing the necessary library
import my_awesome_library as mwl
# Printing the name of the library
print(mwl.__name__) # prints 'my_awesome_library'
# Printing the version of the library
print(mwl.version) # prints '1.0.0'
# Printing the author of the library
print(mwl.author) # prints 'John Doe <[email protected]>'
But what if you don’t have the package installed locally? Or worse yet, what if you don’t even know its name?! No problem pip can help us with that too! Using its “search” command, we can easily retrieve metadata for any installed or available package:
# This script uses the "pip search" command to retrieve metadata for a specified package.
# It is useful when the package is not installed locally or its name is unknown.
# The "pip search" command takes the package name as an argument and returns a list of available packages with their metadata.
# The following command searches for a package named "my_awesome_library" and displays its metadata.
$ pip search my_awesome_library
# The output of the command will be in the following format:
# package_name (version) package_description
# In this case, the output will be:
# my-awesome-library (0.1) Awesomely awesome library for doing stuff
# Note: The package name may not always match the name used in the search command. It is important to check the output carefully to ensure the correct package is being searched for.
This output shows us that there is a package called “my-awesome-library”, which has version 0.1 and a description of “Awesomely awesome library for doing stuff”. Pretty handy!
But what if you don’t even know the name of the package you’re looking for? Well, in that case we can use pip to search for packages based on keywords or other criteria using its “search” command:
# This script uses pip to search for packages based on keywords or other criteria using its "search" command.
# First, we need to specify the keyword or criteria we want to search for.
keyword="awesome library"
# Then, we use the "pip search" command to search for packages that match our keyword.
pip search "$keyword"
# The output will list all the packages that match our keyword, along with their version and description.
# However, the output can be quite long, so we can use the "grep" command to filter the results and only show the package we are interested in.
# In this case, we are interested in the "awesome-library" package, so we use "grep" to filter for that specific package.
pip search "$keyword" | grep "awesome-library"
# The output will now only show the "awesome-library" package, along with its version and description.
# However, the version number is not very descriptive, so we can use the "cut" command to only show the first part of the version number, which is the major version.
# This will give us a better idea of the package's version.
pip search "$keyword" | grep "awesome-library" | cut -d " " -f 2 | cut -d "(" -f 1
# The output will now only show the major version of the "awesome-library" package.
# However, the description is still not very clear, so we can use the "cut" command again to only show the first part of the description, which is the main purpose of the package.
# This will give us a better understanding of what the package is used for.
pip search "$keyword" | grep "awesome-library" | cut -d " " -f 3- | cut -d "." -f 1
# The output will now only show the main purpose of the "awesome-library" package.
# This is a much more concise and informative output, making it easier for us to find the package we are looking for.
This output shows us that there is a package called “awesome-library”, which has version 0.1 and matches our criteria of being both “awesome” and related to a “library”. Pretty cool!