Dictionary in Python

October 5, 2023

Dictionary in Python

In some programming languages, dictionaries are often referred to as associative arrays or hash maps. But In Python, a dictionary is a built-in data structure that allows you to store a collection of key-value pairs. Each key in a dictionary is unique and associated with a specific value.

Python Dictionary

Key:value pairs are contained in the dictionary as an unordered collection enclosed in curly brackets ‘{ }’ and separated by commas ‘ , ‘. When the key is known, dictionaries are designed to retrieve values quickly.

Dictionaries are versatile and widely used in Python for tasks that involve mapping keys to values, such as storing configuration settings, caching data, and more.

Creating a Dictionary

A dictionary can be made by enclosing a list of key-value pairs in curly braces ‘{ }’ and separating them with commas. A colon ‘ : ‘ is used to separate each key-value pair.

Code 1:

Run

# Creating a Dictionary
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
print(dict)

Output :

{'name': 'PrepInsta', 'city': 'Noida'}

Accessing the Values

You can access the values in a dictionary by using the keys as the index.

Code 2 :

Run

#Accessing Value
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
print(dict['name'])

Output :

PrepInsta

Modifying Values

You can change the value associated with a key in a dictionary by simply assigning a new value to that key.

Code 3 :

Run

#Modifying Values
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
dict["city"] = "New York"
print(dict)

Output :

{'name': 'PrepInsta', 'city': 'New York'}

Lists in Python

Deleting items from sorted list

Nested List in Python

Python String join() method

Python String split() Method

Adding New Key – Value Pair

Code 4 :

Run

#Adding new key value pair
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
dict["category"] = "edtech"
print(dict)

Output :

{'name': 'PrepInsta', 'city': 'Noida', 'category': 'edtech'}

Removing Key – Value Pair

By following the key you want to delete with the del keyword, you can delete key-value pairs from a dictionary.

Code 5 :

Run

#Removing key value pair
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
del dict["city"] 
print(dict)

Output :

{'name': 'PrepInsta'}

Checking if a Key Exists

You can check if a key exists in a dictionary using the in keyword.

Code 6 :

Run

#Checking if a key exists
dict = {
    "name": "PrepInsta",
    "city": "Noida"
}
if "name" in dict:
    print("Yes, This is in your dictionary")

Output :

Yes, This is in your dictionary

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Dictionary in Python