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Python provides another composite data type called a dictionary, which is similar to a list in that it is a collection of objects. Here’s what you’ll learn in this tutorial: You’ll cover the basic characteristics of Python dictionaries and learn how to access and manage dictionary data.
- Dictionaries in Python
Python provides a composite data type called a dictionary,...
- Take The Quiz
Test your understanding of Python dictionaries. Python...
- Dictionaries in Python
- Creating A Python Dictionary
- Access and Delete A Key-Value Pair
- Using Try… Except
- Valid Dictionary Values
- Valid Dictionary Keys
- More Ways to Create A Python Dictionary
- Dictionary View Objects
- Merging Dictionaries
- Comparing Python Dictionaries
- Conclusion
Let’s look at how we can create and use a Python dictionary in the Python REPL: A dictionary is created by using curly braces. Inside these braces, we can add one or more key-value pairs. The pairs are separated by commas when adding more than one key-value pair. The first dictionary in our example associates keys (names like Jack and Pete) with va...
Now that you’ve seen how to initialize a dictionary, let’s see how we can add and remove entries to an already existing one:
If a requested key does not exist, an exception of type KeyErroris thrown: If you know data can be missing, e.g., when parsing input from the outside world, make sure to surround your code with a try ... except KeyError. I’ve explained this in detail in the best practices section of my article on try… except. In that article, I also explain the con...
You can put anything in a dictionary. You’re not limited to numbers or strings. In fact, you can put dictionaries and Python listsinside your dictionary and access the nested values in a very natural way: Python’s JSON decoding and encoding libraryuses this feature of Python when parsing more complex JSON documents. It creates nested trees of lists...
You can go pretty wild on your dictionary keys, too. The only requirement is that the key is hashable. Mutable types like lists, dictionaries, and sets won’t work and result in an error like: TypeError: unhashable type: ‘dict’. Besides this limitation, you can use all data types as a dictionary key, including native types like a tuple, float and in...
Depending on your data source, there are more advanced ways to initialize a dictionary that might come in handy.
Some built-in dictionary methods return a view object, offering a window on your dictionary’s keys and values. Before we start using such view objects, there’s an important concept you need to understand: values in a view object change as the content of the dictionary changes.
If you’re running Python 3.9 or later, you can use the newly introduced merging operator for dictionaries: If you’re still on a Python version between 3.5 and 3.9, you can merge two dictionaries using the following method:
If you need to compare two dictionaries, you can use a comparison operator like this: This looks and sounds trivial, but it’s not! A dictionary can contain objects of any type, after all! Consequently, Python has to walk through all the keys and values and individually compare them. You might wonder if a dictionary with the same keys and values ins...
You’ve learned what a Python dictionary is, how to create dictionaries, and how to use them. We’ve examined many practical use cases involving Python dictionaries with example code. If there’s still something missing, or you simply want to learn even more about dictionaries, you can head over to the official manual page at Python.org.
3 days ago · Dictionaries are a game-changer in Python. Blazingly fast lookup times, flexibility in structure, and clarity in syntax makes them a favorite for expert Pythonistas. In this complete guide, we‘ll dive deep into everything you need to know to harness the power of Python dictionaries for your development projects.
Apr 1, 2022 · In this Python tutorial, you'll learn how to create a Python dictionary, how to use its methods, and dictionary comprehension, as well as which is better: a dictionary or a list. To get the most out of this tutorial, you should be already familiar with Python lists, for loops, conditional statements, and reading datasets with the reader() method.
I'd like to call a function in python using a dictionary with matching key-value pairs for the parameters. Here is some code: d = dict(param='test') def f(param): print(param) f(d) This prints {'param': 'test'} but I'd like it to just print test.
A dictionary is an ordered collection of items (starting from Python 3.7), therefore it maintains the order of its items. We can iterate through dictionary keys one by one using a for loop.
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Sep 3, 2023 · In this article, we will dive into the world of Python dictionaries, exploring their features, operations, and practical use cases, accompanied by code examples.
