Master Python Dictionaries: Tips, Tricks, and Best Practices

Explore the power of immutable sequences with Python tuples. Discover tips, tricks, and common uses to optimize your code.

Dict: A Python dictionary (dict) is an unordered collection of items. Each item is a key-value pair, where keys are unique within a dictionary and are used to store and retrieve values.

# Dictionary with initial key-value pairs 
car_details = {"brand": "Ford", "model": "Mustang", "year": 1964}

Removing a key and retrieving its value:

car_details = {"brand": "Ford", "model": "Mustang", "year": 1964}
year = car_details.pop("year")
print(year)          # Output: 1964

Merging Dictionaries:

car_details = {"brand": "Ford", "model": "Mustang"}
car_details2 = {"year": 1964}

merged_dict = car_details | car_details2
# Output: {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}

Sorting a Dictionary:

# Sorting by keys
sorted_by_keys = dict(sorted(car_details.items()))

# Sorting by values (let's say by the length of values for this example)
sorted_by_values = dict(sorted(car_details.items(), key=lambda item: len(str(item[1]))))

Dictionary Unpacking:

def show_car_details(model, year):
    print(f"Model: {model} and Year: {year}")

car_info = {"model": "Mustang", "year": 1964}
show_car_details(**car_info)  
# Output: "Model: Mustang and Year: 1964"

Immutable Dictionary with types.MappingProxyType:

from types import MappingProxyType

car_details = {"model": "Mustang", "year": 1964}
# Immutable version of a Dictionary

immutable_car_details = MappingProxyType(car_details)
immutable_car_details["color"] = "Red" 
# This would raise a TypeError

---

The `setdefault()` method:

• The setdefault method in a Python dictionary is used to retrieve the value of a specified key if it exists. If the key doesn't exist, it inserts the key with a specified default value and then returns that default value.

# General syntax:
dict.setdefault(key, default_value)

Retrieving an existing key:

car_details = {"model": "Mustang", "year": 1964}
model = car_details.setdefault("model", "Bronco")
print(model)          
# Output: "Mustang"

print(car_details)    
# Output: {'model': 'Mustang', 'year': 1964}

Adding a new key with default value:

car_details = {"model": "Mustang", "year": 1964}
color = car_details.setdefault("color", "Red")
print(color)          
# Output: "Red"

print(car_details)    
# Output: {'model': 'Mustang', 'year': 1964, 'color': 'Red'}

These tricks should help you get the most out of Python dictionaries, enhancing both your efficiency and the readability of your code!