Built-in Dictionary Functions & Methods in Python

Python dictionaries come with built-in functions and methods that make working with key-value pairs efficient and straightforward. These functions help you manipulate, query, and transform dictionary data.

Built-in Dictionary Functions

Python provides several built-in functions that work with dictionaries ?

len() Function

student = {'name': 'Alice', 'age': 20, 'grade': 'A'}
print(len(student))

3

str() Function

student = {'name': 'Alice', 'age': 20}
print(str(student))
print(type(str(student)))

{'name': 'Alice', 'age': 20}
<class 'str'>

type() Function

student = {'name': 'Alice', 'age': 20}
print(type(student))

<class 'dict'>

Dictionary Methods

Dictionary methods are called directly on dictionary objects and provide powerful ways to manipulate data ?

Basic Operations

# clear() - removes all elements
student = {'name': 'Alice', 'age': 20}
student.clear()
print(student)

# copy() - creates a shallow copy
original = {'a': 1, 'b': 2}
copied = original.copy()
print(copied)

{}
{'a': 1, 'b': 2}

Accessing Values Safely

student = {'name': 'Alice', 'age': 20}

# get() - returns value or default
print(student.get('name'))
print(student.get('grade', 'Not Available'))

# setdefault() - gets or sets default value
student.setdefault('grade', 'A')
print(student)

Alice
Not Available
{'name': 'Alice', 'age': 20, 'grade': 'A'}

Dictionary Views

student = {'name': 'Alice', 'age': 20, 'grade': 'A'}

# keys() - returns dictionary keys
print(list(student.keys()))

# values() - returns dictionary values  
print(list(student.values()))

# items() - returns key-value pairs
print(list(student.items()))

['name', 'age', 'grade']
['Alice', 20, 'A']
[('name', 'Alice'), ('age', 20), ('grade', 'A')]

Updating Dictionaries

student = {'name': 'Alice', 'age': 20}
additional_info = {'grade': 'A', 'major': 'Computer Science'}

# update() - adds key-value pairs from another dictionary
student.update(additional_info)
print(student)

# fromkeys() - creates dictionary from keys
subjects = dict.fromkeys(['Math', 'Science', 'English'], 'Pending')
print(subjects)

{'name': 'Alice', 'age': 20, 'grade': 'A', 'major': 'Computer Science'}
{'Math': 'Pending', 'Science': 'Pending', 'English': 'Pending'}

Summary of Dictionary Functions and Methods

Conclusion

Python's built-in dictionary functions and methods provide comprehensive tools for dictionary manipulation. Use get() for safe access, update() for merging dictionaries, and view methods like keys() and items() for iteration.