Python Dict Get Value by Key Default

Dictionaries are a fundamental data structure in Python, providing a flexible way to store and retrieve key-value pairs. When working with dictionaries, there are situations where you want to retrieve a value for a given key, but you also want to provide a default value in case the key is not present. In this article, we’ll explore various methods to achieve this.

Python Dict Get Value by Key Default

Below, are the methods to Python Dict Get Value by Key Default.

• Using get() Method
• Using lambda Function
• Using setdefault() Method
• Using Conditional Expression

Python Dict Get Value by Key Default Using get() Method

The get() method is a built-in method for dictionaries that allows you to retrieve the value for a specified key. It takes two arguments – the key you want to retrieve and a default value to return if the key is not found.

Python3

# Example using get() method
my_dict ={ 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}

# Using get() with a default value of 0
value = my_dict.get('geek', 0)
print("value of the key", value)

Output

value of the key 4

Python Dict Get Value by Key Default Using lambda Function

The defaultdict from the collections module is a powerful tool for handling default values for dictionary keys. Combining defaultdict with a lambda function allows you to specify a default value for keys that don’t exist.

Python3

from collections import defaultdict

# Example using lambda and defaultdict
my_dict = defaultdict(lambda: 0)
my_dict['apple'] = 5
my_dict['banana'] = 3

# Accessing a key that doesn't exist
value = my_dict['grape']
print("value of the key", value)

Output

value of the key 0

Python Dict Get Value by Key DefaultUsing setdefault() Method

The setdefault() method is a dictionary method that sets the default value for a key if the key is not present. It returns the value for the key, and if the key is not found, it inserts the key with the specified default value.

Python3

# Example using setdefault() method
my_dict = { 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}

# Using setdefault() with a default value of 0
value = my_dict.setdefault('geek', 0)
print("value of the key",value)

Output

value of the key 4

Python Dict Get Value by Key Default Using Conditional Expression

Python allows the use of conditional expressions to achieve the same result. This method is concise and can be easily customized for different default values.

Python3

Dictionary ={ 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}
key = "geek"

#retrieving the value of the provided key using conditional expression
value = Dictionary[key] if key in Dictionary else "None"

print("value of the key", key,"=", value)

Output

value of the key geek = 4

Conclusion

In conclusion, Python provides several methods to retrieve values from dictionaries with default values for keys that may not exist. The choice of method depends on the specific requirements of your code, and each method has its own advantages. Whether you prefer the simplicity of get(), the versatility of defaultdict, the directness of setdefault(), or the conciseness of conditional expressions, Python offers a variety of tools to handle default values in dictionary lookups.