Passing a Dictionary as Arguments to a Function in Python

Dictionaries in Python are powerful data structures that store key-value pairs. You can pass them as arguments to functions in several ways, making your code more flexible and efficient when working with structured data.

Basic Dictionary as Function Argument

The simplest way is to pass a dictionary directly as a parameter ?

def print_person_info(person):
    print(f"Name: {person['name']}")
    print(f"Age: {person['age']}")

person_data = {'name': 'Alice', 'age': 30}
print_person_info(person_data)

Name: Alice
Age: 30

Modifying Dictionary Values in Functions

Since dictionaries are mutable, changes made inside the function affect the original dictionary ?

def update_age(person):
    person['age'] += 1
    return person

person_data = {'name': 'Bob', 'age': 25}
print(f"Before: {person_data}")
update_age(person_data)
print(f"After: {person_data}")

Before: {'name': 'Bob', 'age': 25}
After: {'name': 'Bob', 'age': 26}

Using ** to Pass Dictionary as Keyword Arguments

The double asterisk operator unpacks dictionary keys as parameter names ?

def create_profile(name, age, city):
    return f"{name} is {age} years old and lives in {city}"

user_info = {'name': 'Carol', 'age': 28, 'city': 'New York'}
profile = create_profile(**user_info)
print(profile)

Carol is 28 years old and lives in New York

Iterating Over Dictionary in Functions

You can loop through dictionary items to process all key-value pairs ?

def display_all_info(data):
    for key, value in data.items():
        print(f"{key.title()}: {value}")

student = {'name': 'David', 'grade': 'A', 'subject': 'Math'}
display_all_info(student)

Name: David
Grade: A
Subject: Math

Handling Missing Keys Safely

Use the get() method to avoid KeyError when accessing dictionary values ?

def safe_print_info(person):
    name = person.get('name', 'Unknown')
    age = person.get('age', 'Not specified')
    print(f"Name: {name}, Age: {age}")

incomplete_data = {'name': 'Eve'}
safe_print_info(incomplete_data)

Name: Eve, Age: Not specified

Comparison of Methods

Conclusion

Passing dictionaries to functions provides flexibility in handling structured data. Use direct passing for key-based access, ** unpacking when keys match parameters, and get() for safe key access.