Python Dictionary and its operations

Hello everyone, Welcome back to proramminginpython.com. Here in this post am going to introduce you to one of the popular Python data types – Dictionary. Lists and Tuples are some of the other data types. Dictionaries are indexed by keys and can be of any immutable type. These are unordered key-value pairs with unique keys.

A dictionary can be created simply by writing curly braces {} an example dictionary will look like {'key1': 'value1', 'key2': 'value2'}

Now let’s go through the operations that can be performed on dictionaries.

You can also watch the video on YouTube here

Program on GitHub

Create Dictionary

I will create a dictionary named my_infoand add some key-value pairs to it.

# add elements to dictionary
my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

and print it.

# print dictionary
print(my_info)

Program on GitHub

Accessing Values

Now I can access the elements in the dictionary by their key, here I will print the value of the key 'Name'.

my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

# print value of a key
print(my_info['Name'])

Modifying values

I can also modify the existing elements in the dictionary, here I will modify the value of key 'Age'

my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

# modify elements in dictionary
my_info['Age'] = 24
print(my_info)

Program on GitHub

Length of dictionary

I can also find the length of the dictionary, using the built-in method len() which gives the total number of items in the dictionary.

my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

# length of dictionary
print(len(my_info))

Delete elements

I can also delete a particular key from a dictionary, here I will delete key 'Website'

my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

# delete a particular key 
del my_info['Website'] 
print(my_info)

Similarly, I can remove all the elements using a function called clear() which empties all the elements in the dictionary

# removes all elements in dictionary 
my_info.clear()

I can also delete the entire dictionary,

# delete entire dictionary 
del my_info

These are some of the operations that can be performed on dictionaries.

Program on GitHub

The complete code for the above snippets,

__author__ = 'Avinash'

# add elements to dictionary
my_info = {
    'Name': 'Avinash',
    'Age': 23,
    'Gender': 'Male',
    'Location': 'India',
    'Website': 'programminginpython.com'
    }

# print dictionary
print(my_info)

# print value of a key
print(my_info['Name'])

# modify elements in dictionary
my_info['Age'] = 24
print(my_info)

# length of dictionary
print(len(my_info))

# delete a particular key
del my_info['Website']
print(my_info)

# removes all elements in dictionary
my_info.clear()
print(my_info)

# delete entire dictionary
del my_info