Python Dictionaries (Full Explained)

In Python, Dictionaries allows us to store data in key: value pairs. Dictionary is one of the 4 built-in data types in python, the other 3 are Lists, Tuples and Sets.

Dictionaries are mutable and ordered collection of key-value pairs. They can also contain elements of different Data type. Here is an example of how you can create a dictionary in Python.

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
print(fruit_dict)
#Outputs: {'Mango': 100, 'Apple': 150, 'Banana': 80, 'Orange': 'Fifty'}

In an above example, the dictionary (fruit_dict) contains four key-value pairs. The keys are "Mango", "Apple", "Banana" and "Orange", and the corresponding values are 100, 150, 80 and "Fifty".

You can also access the values in a dictionary by using the keys as the index. Here is an example:

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
print (fruit_dict["Mango"]) #Outputs: 100
print (fruit_dict["Orange"]) #Outputs: Fifty

Change Dictionary Items

In Python, we can change the value of a specific item by simply referring to it’s index name. Here is an example:

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
#changing the dictionary item 
fruit_dict["Banana"] = 160
print (fruit_dict) #Outputs: {'Mango': 100, 'Apple': 150, 'Banana': 160, 'Orange': 'Fifty'}

Add Item to a Dictionary

In Python, we can add new items to a dictionary by simply using a new index key and assigning any value to it. Here is an example:

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
#Adding new item to a dictionary
fruit_dict["Grapes"] = 120
print (fruit_dict) #Outputs: {'Mango': 100, 'Apple': 150, 'Banana': 80, 'Orange': 'Fifty', 'Grapes': 120}

Remove Item from a Dictionary

In Python, we can remove an item from a dictionary by various ways. But most of the programmers use pop() method. Below in an example let’s write a code to remove an item from a dictionary.

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
#Removing item from a dictionary
fruit_dict.pop("Orange")
print(fruit_dict)

Check if a Key is Present in a Dictionary

To check if an key is present in a dictionary or not we can use the python membership operator. It returns True if a Key is present in a Dictionary, otherwise False. Here is an example:

Example

fruit_dict = {"Mango": 100, "Apple": 150, "Banana": 80, "Orange": "Fifty"}
#Check if a key is present in a dictionary
print("Mango" in fruit_dict) #Outputs: True
print ("Grapes" in fruit_dict) #Outputs: False
print (100 in fruit_dict) #Outputs: False

Remember that we can only check if a key is present in a dictionary, not a value. That is why it returns False when we try to check the value of Mango key (100).

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Python Dictionaries (Full Explained)