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| Python Dictionary Master Guide | Beginners to Advanced in 2026 |
Dictionary Definition in Python
Dictionary: A dictionary is an unordered collection of data of different data types. Dictionary data can be changed. A dictionary is created using curly brackets. Dictionary items are in the form of key-value pairs.
A dictionary in python is an unordered mutable and indexed collection of data that stores key-value pairs. Each key in a dictionary must be unique and immutable (like List, a string, number, or tuple) while the values can be of any data type including lists, dictionaries. Dictionaries are enclosed in curly braces {} with each key separated from its value by a colon (:).
Syntax of Dictionary in Python
Dictionary Example Program in Python
print(data) print(type(data)) ============OUTPUT============ {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} <class 'dict'> |
Dictionary Methods in Python
| Len Function: It can be used to get the length numbers of elements in dictionary items. |
| Key Function: The keys() method in python is a built-in dictionary method used to return a view object containing all the keys of a dictionary. |
| Items Function: The items() method in python is a built-in dictionary method used to return a view object of all key-value pairs in a dictionary. |
| Values Function: The values() method in python is a built-in dictionary method used to return a view object containing all the values stored in a dictionary. |
| Get Function: The get() method in python is a built-in dictionary method used to retrieve the value of a specified key. |
| Update Function: The update() method in python is a built-in dictionary method used to add new key-value pairs to a dictionary or modify existing ones. |
| Pop Function: The pop() method in python is a built-in dictionary method used to remove a specified key from a dictionary and return its value. |
| Clear Function: The clear() method in python is a built-in dictionary method used to remove all items (key-value pairs) from a dictionary, leaving it empty. |
| Copy Function: The copy() method in python is a built-in dictionary method used to create a shallow copy of a dictionary. |
| Fromkeys Function: The fromkeys() method in python is a built-in dictionary method used to create a new dictionary from a sequence of keys. |
Dictionary Key Function Python
Key: We can access items of dictionary using key method. Key is a unique identifier used to store the value and access data.
Example of Dictionary Key in Python
print("Student Name:",data["name"]) ============OUTPUT============ Student Name: Jiocoding |
Printing key and value. Access values of dictionary using loop printing key.
How to Print Key using For Loop
for key in data: print(key) ============OUTPUT============ name age City Language |
How to print key value pair using Loop
for key in data: print(key,"of Company Data:",data[key]) ============OUTPUT============ name of Company Data: Jiocoding age of Company Data: 33 City of Company Data: Noida Language of Company Data: Python |
Dictionary Get Function in Python
We can also access items of dictionary using get() function. The get() method in Python dictionaries returns the value for a given key and avoids raising an error if the key is missing by returning None or a specified default value instead.
Example of Dictionary in Python with Output
print("Student Name:",data.get("name")) ============OUTPUT============ Student Name: Jiocoding |
How to use update Function in Dictionary in Python
Update items of dictionary We can change the value of dictionary. The update() method in Python is a built-in dictionary method used to add new key-value pairs or modify existing ones using another dictionary or an iterable of key-value pairs.
Example of Update in Python
print("Before Update Dictionary") print(data) data["City"]="Delhi" print("After Update Dictionary") print(data) ============OUTPUT============ Before Update Dictionary {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After Update Dictionary {'name': 'Jiocoding', 'age': 33, 'City': 'Delhi', 'Language': 'Python'} |
Dictionary Length Python
Length of dictionary: len() function is used to get length of dictionary. The length of a dictionary refers to the number of key-value pairs it contains. Python does not have a special length method for dictionaries. It is uses the built-in len() function to find the number of items in a dictionary.
Example of Dictionary in Python with Output
print("Length of dictionary:",len(data)) ============OUTPUT============ Length of dictionary: 4 |
Add New Dictionary Item Python
we can also add new item to a dictionary using key. A new item can be added to a dictionary by assigning a value to a new key using square bracket notation. If the key does not already exist, python creates a new key-value pair in the dictionary.
Example of Add new Dictionary Item
print("Before Add New Dictionary Item") print(data) data["Courses"]="Python_Language" print("After Before Add New Dictionary Item") print(data) ============OUTPUT============ Before Add New Dictionary Item {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After Before Add New Dictionary Item {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python', 'Courses': 'Python_Language'} |
Dictionary Pop Method in Python
The pop() method in Python is a built-in dictionary method used to remove a specified key and return its corresponding value. If the key is not found and no default value is provided raises a KeyError. Pop() function is used to remove specified item from a dictionary.
Example of Dictionary in Python with Output
print("Before Delete Dictionary Items") print(data) data.pop("age") print("After Delete Dictionary Items") print(data) ============OUTPUT============ Before Delete Dictionary Items {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After Delete Dictionary Items {'name': 'Jiocoding', 'City': 'Noida', 'Language': 'Python'} |
Del Method in Dictionary Python
del keyword is also used to remove specified item from a dictionary.
Example of Del Method Dictionary in Python
print("Before using Del Dictionary Items") print(data) del data["age"] print("After using Del Dictionary Items") print(data) ============OUTPUT============ Before using Del Dictionary Items {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After using Del Dictionary Items {'name': 'Jiocoding', 'City': 'Noida', 'Language': 'Python'} |
Delete dictionary: del keyword is also used to delete dictionary completely.
Example of Delete Dictionary in Python
print("Before Delete Dictionary Items") print(data) del data print("After Delete Dictionary Items") print(data) ============OUTPUT============ Before Delete Dictionary Items {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After Delete Dictionary Items NameError: name 'data' is not defined |
Dictionary Clear Method in Python
clear() function is used to clear or empty the dictionary. The clear() method in python is a built-in dictionary method used to remove all items (key-value pairs) from a dictionary, leaving it empty.
Example of Clear Function in Python
print("Before using clear Dictionary Items") print(data) data.clear() print("After using clear Dictionary Items") print(data) ============OUTPUT============ Before using clear Dictionary Items {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After using clear Dictionary Items {} |
Nested Dictionary in Python
A nested dictionary in Python is a dictionary inside another dictionary. It means one or more values in a dictionary are themselves dictionaries.
Nested Dictionary in Python Example
"Jiocoding":{ "id":465473543, "Website Name":"Jiocoding", "City":"Noida" }, "Ramesh":{ "id":4368644, "percent":89.6, "City":"Delhi" } } print("Jiocoding Data:",student_data["Jiocoding"]) print("Ramesh Data:",student_data["Ramesh"]) ============OUTPUT============ Jiocoding Data: {'id': 465473543, 'Website Name': 'Jiocoding', 'City': 'Noida'} Ramesh Data: {'id': 4368644, 'percent': 89.6, 'City': 'Delhi'} |
Dictionary Copy Method in Python
The copy() method in python is a built-in dictionary method used to create a shallow copy of a dictionary. It returns a new dictionary with the same key-value pairs as the original dictionary.
Example of Dictionary Copy Method in Python
print(data) data1=data.copy() print(data1) ============OUTPUT============ {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} |
Dictionary Fromkeys Function in Python
This method creates a new dictionary with specified key and value. The fromkeys() method in Python is a built-in dictionary method used to create a new dictionary from a sequence of keys with all keys assigned the same specified value.
Example of Dictionary Fromkeys in Python
dict_data1=dict.fromkeys(dataset) print("Without Value:",dict_data1) dict_data2=dict.fromkeys(dataset,100) print("With Value:",dict_data2) ============OUTPUT============ Without Value: {'data1': None, 'data2': None, 'data3': None} With Value: {'data1': 100, 'data2': 100, 'data3': 100} |
Dictionary Item Method in Python
It returns all the key-value pair of the dictionary.
Example of Dictionary Items in Python
print("Dictionary Key:",data.items()) ============OUTPUT============ Dictionary Key: dict_items([('name', 'Jiocoding'), ('age', 33), ('City', 'Noida'), ('Language', 'Python')]) |
Set Default Method in Dictionary Python
This method is used to set a default value to a key. If the specified key is present in the dictionary then it returns its value.
Example of Dictionary Default Method 1 in Python
x=data.setdefault("name") print(data) print(x) ============OUTPUT============ {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} Jiocoding |
If the specified key is not present in the dictionary then it insert key into dictionary with default value 'None'. We can also set value of key using setdefault function.
Example of Dictionary Default Method 2 in Python
print(data) x=data.setdefault("Google") print(data) ============OUTPUT============ {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python', 'Google': None} |
Dictionary Values Method in Python
It returns all the values of the dictionary. A values() method in python is a built-in dictionary method used to return a view object containing all the values in a dictionary. The view object reflects changes made to the dictionary.
Example of Dictionary Values Method in Python
print("Dictionary Data:",data.values()) ============OUTPUT============ Dictionary Data: dict_values(['Jiocoding', 33, 'Noida', 'Python']) |
Dictionary Update Method in Python
This method updates the dictionary with the key and value pairs. The update() method in python updates a dictionary by adding new key-value pairs or modifying existing ones. Existing keys are updated and new keys are added to the dictionary.
Example of Update Dictionary in Python
print("Before Update Dictionary Data") print(data) data.update({"pincode":435454}) print("After Update Dictionary Data") ============OUTPUT============ Before Update Dictionary Data {'name': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python'} After Update Dictionary Data {'sid': 'Jiocoding', 'age': 33, 'City': 'Noida', 'Language': 'Python', 'pincode': 435454} |
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