This article is part of the series of tutorials about data types in Python. Today we will learn about Python dictionaries together. Let’s follow this article to the end. First, we need to understand what a Python dictionary is.
What is a Python dictionary?
A dictionary in Python is a collection of keys and values used to store data whereas other data types can only keep a single value as an element.
The dictionary is another essential data type included with Python. In some other languages, dictionaries are known as associative arrays or associative memories. Dictionaries are indexed by keys, which can be any immutable type; integers and strings can always be keys.
This contrasts with sequences, which are indexed by a range of numbers. Strings, numbers, and tuples are the only objects that can be used as keys; any other mutable objects, whether directly or indirectly, prevent a tuple from serving as a key.
Since lists in Python can be changed in place via slice assignments, index assignments, or methods like extend() and append(), lists cannot be used as keys. You can visit learnshareit to learn more about Python lists.
How to create Python dictionaries?
In Python, we must enclose a sequence of elements inside curly brackets and separate them with a comma to create a dictionary. Pairs of values are stored in the dictionary, where one pair element is the Key, and the other is its Key: value.
Keys must be immutable and cannot be repeated, but the dictionary’s values can be duplicated and can be of any data type.
Please keep in mind that dictionary keys are case-sensitive, which means that keys with the same name but different cases will be processed differently.
You may also build a dictionary with the built-in function dict(). An empty dictionary may be built by just using curly brackets.
Some methods in Python dictionaries
Let’s check over some methods for working with dictionaries now.
- clear(): Removing all the values from the dictionary
- copy(): Returning a copy of the dictionary
- keys(): Returning a list including the dictionary’s keys
- pop(): Removing the element with the defined key
- get(): Returning the value of the defined key
- items(): Returning a list including a tuple for each key-value pair
- values(): Returning a list of all the values of the dictionary
- pop item(): Removing the last inserted key-value pair
- update(): Updating dictionary with defined key-value pairs
Multiple methods can be used to add items. Dict[Key] = “Value,” one value can be added to a dictionary at a time by defining the value and the key together. Using the built-in update() method, we can update an existing value in a Dictionary. We also can add nested key values to an existing dictionary.
Note: If the key-value combination already exists, the value is updated when adding a value. If not, a new key and value are added to the dictionary.
There are no limitations on dictionary values. They may be any Python object, whether they are built-in or user-defined. The same does not apply to keys, though. There are two crucial things to keep in mind about dictionary keys:
- Only one entry is allowed per key. This implies that duplicate keys are not permitted. The most recent assignment will be chosen if we encounter duplicate keys during the assignment.
- Keys must be unchangeable. In other words, you cannot use dictionary keys like [‘key’] but can use strings, numbers, or tuples.
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