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Dictionary In Python

In this article, we will discuss dictionaries in Python.

What Is A Dictionary?

The dictionary is a collection of key-value pair that stores the data related to each other. For example, if you want to store information about name, age, and address then a dictionary is the right choice for you.

Syntax

Variable_name  = {“key name1”: value1, “key name 2: value 2………….}

You can access the value using

Variable_name[“key name”]

Example

Consider the following code

personInformation = {"Name": "Karan", "Age":37}

print(personInformation)

print(personInformation["Name"])

When you run the above code, you will get the following output: -

Picture showing your first dictionary in python

Delete From The Dictionary

You can delete the key using the ‘del’ command in Python. Consider the following program: -

personInformation = {"Name": "Karan", "Age":37}

print(personInformation)


# Delete Key from dictionary

del personInformation ["Age"]

print(personInformation)

In the above code, we are deleting the key ‘Age’. Once you run this program, you will get the following output.

Picture showing the dictionary after deleting the Age key from it

Clear All Items From The Dictionary

You can use the clear function to clear all items from the dictionary. Consider the following example: -

personInformation = {"Name": "Karan", "Age":37}

print(personInformation)

# Clear all items from dictionary
personInformation.clear()
print(personInformation)

Once you run the code, you will get the following output.

Picture showing the dictionary after clearing all items from it

Loop Through All Key-Value Pair In The Dictionary

The following code is for looping through key-value pair in the dictionary.

personInformation = {"Name": "Karan", "Age":37}

for k,v in personInformation.items():
        print("Key:",k,", Value:",v)

Once you run the above code, you will get the following output: -

Picture showing the output of Loop through all key-value pair in dictionary

The Uniqueness Of Elements In The Dictionary

Each element in the dictionary is unique. Even if you try to create a dictionary with a duplicate key and try to print it, it will display only 1 key. Consider the following example: -

dict = {"key1":1, "key1":2}
print(dict)

This code will give the following output.

Picture shows how the print function in python removes duplicacy of keys in the dictionary

Nested Dictionary

In Python, you can nest one dictionary into another. Consider the following example: -

nested_dictionary = {"name": "Karan", "address": {"city":"Gurgaon", "country": "India"}}
                         

print("Name:", nested_dictionary["name"])
print("city:", nested_dictionary["address"]["city"])
print("country:", nested_dictionary["address"]["country"])

In the above code, we have another dictionary ‘address’ inside nested_dictionary. Once you run the above code, you will get the following output: -

Picture showing the nested dictionary in python

Delete The Whole Dictionary

You can use the "del" method to delete the dictionary. Consider this code

personInformation = {"Name": "Karan", "Age":37}


print(personInformation)

del(personInformation)

print(personInformation)

The second print statement gives an error as the dictionary is deleted.

Picture showing the error message as the code is trying to print the deleted dictionary

Posted By -	Karan Gupta

Posted On -	Thursday, February 14, 2019

Updated On -	Saturday, September 25, 2021

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