Python Dictionary

The four data types in Python are List, Tuple, Dictionaries, and Set. On this page, we’ll be discussing the Python Dictionary. However, for a clear understanding of the other three, refer to Python Data Types. ln python, it’s frequent that you store your well-organized data under a keyword while Coding.

In this interaction, you’ll be learning in simple and clear terms:

What is the Python Dictionary?

Types of the Python dictionary

Characteristics of the Python

Dictionary

Creating a python Dictionary

Operations on python Dictionary

Built-in functions

Finally, you’ll be free to manifest the knowledge through practice

Contents

What is a Python Dictionary?

Simply stated, a Python Dictionary is the collection of ordered items within curly brackets {}, a key: Values. It is used to store values in key:value pairs.

The python Dictionary can be invoked by writing the keyword( that is the word that represents the content value). For the knowledge, the Python Dictionary became an ordered collection from python 3.7 anything backward was not ordered.

Example of a python dictionary

Vehicles = {"Land": "Taxi", "Bicycle": "Motorcycle", "Train": "Bus"}

The python dictionary as a data type has features that you should take cognizance

Characteristics of the Python Dictionary

Dictionaries keywords are ordered

Key Values are mutable but keywords must be immutable and the dictionary does not allow duplicates

Python Dictionaries are within Curly brackets{}

Python Dictionary is case sensitive, Man and man are taken as different value

Python Dictionary Values can be of any data type and can repeat

The above are some major characters of the Python dictionary. We’ll be seeing some examples in correspondence to its characters. Before then, let’s Open a Dictionary

Creating a python Dictionary

Before you have access to other operations of the python dictionary, you must create a dictionary first. Good thing is, you can create a dictionary with the dict() function.

Example 1: Creating a dictionary with the dict() function

Python Input:

# empty dictionary
my_dict = {}
# dictionary with integer keys
my_dict = {1: 'pen', 2: 'pencils'}
# dictionary with mixed keys
my_dict = {'name': 'Tanya', 1: [2, 4, 3]}
# using dict()
my_dict = dict({1:'pen', 2:'pencils'})
# from sequence having each item as a pair
my_dict = dict([(1, 'pen'), (2,' pencils')])

At this point, you’re set for the journey ahead, Let’s Python up!

Accessing Dictionary Elements in Python

Elements in Python Dictionary can be accessed using two methods which are:

Square brace [ ]. This raises KeyError when a key is found in the dictionary

get() function: It gives a non. return of the key is not found

Example:

Python Input:

# get vs [ ] for retrieving elements
my_dict = {'Vehicle': 'car', 'bicycle': plane}

# Output: Jack

print(my_dict['vehicle'])
# Output: 26

print(my_dict.get('plane'))
# Trying to access keys that don't exist throws an error
# Output None

print(my_dict.get('jet'))
# KeyError

print(my_dict['jet'])

Output:

Car
plane
None

Traceback (most recent call last):
  File "<string>", line 15, in <module>
    print(my_dict['jet'])
KeyError: 'jet'

The statement above agrees with the box bracket [] and the get() function Methods

Modifying the Python Dictionaries

You can add new items to the python dictionary or change an existing value to another by using the assign function (=). In doing this, if the key is available, the existing value gets updated. If the key isn’t available, a new key: value is added to the dictionary.

Example:

Python Input:

#!/usr/bin/python3
dict = {'Land': 'Train', 'Water': Ship, 'Sky': 'Plane'}
dict['Land'] = Train; # update existing entry
dict['Space'] = "Spaceship" # Add a new entry
print ("dict['Land']: ", dict['Land'])
print ("dict['Space']: ", dict['Space'])

Output:

dict['Land']:  Train
dict['Space']:  Spaceship

Carefully study the results above. However, there are more reasons ahead. You shouldn’t stop smelling roses here.

Deleting Python Dictionary

There’s a provision for item deletion in Python. You can either remove an isolated item from the dictionary using the pop() function or you can remove a key:value pair item from the dictionary.

In some cases where necessary, you can get rid of the entire item by consulting the clear() function. However, when things get serious, and you want to get rid of items meticulously, you can use the del keywords to remove individual items or get rid of the entire Dictionary at once.

Example:

Python Input:

# Removing elements from a dictionary
# create a dictionary
triangle = {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
# remove a particular item, returns its value
# Output: triangle
print(triangle. pop(4))
# Output: {1: 1, 2: 4, 3: 9, 5: 25}
print(triangle)
# remove an arbitrary item, return (key, value)
# Output: (5, 25)
print(triangle.   pop item())
# Output: {1: 1, 2: 4, 3: 9}
print(triangle)
# remove all items
triangle.clear()
# Output: {}
print(triangle)
# delete the dictionary itself
del triangle
# Throws Error
print(triangle)
Output:
16
{1: 1, 2: 4, 3: 9, 5: 25}
(5, 25)
{1: 1, 2: 4, 3: 9}
{}
Traceback (most recent call last):
  File "<string>", line 30, in <module>
    print(triangle)
NameError: name 'triangle' is not defined