Why Use Python's `dict.get()` Instead of `dict[key]`?

Understanding the Advantages of dict.get() over dict[key]

When working with Python dictionaries, you may have noticed the dict.get() method, which retrieves a value associated with a key. While you could simply use dict[key] to get the same result, dict.get() offers an important advantage.

Default Value Handling

dict.get() allows you to easily provide a default value if the key you're looking for doesn't exist in the dictionary. This is achieved through the second optional parameter:

dictionary.get("bogus", default_value)

Here, if the key "bogus" doesn't exist, the method will return the specified default_value instead of raising a KeyError.

On the other hand, if you use dict[key] for a missing key:

dictionary["bogus"]

you will get a KeyError exception.

Examples

Consider a dictionary:

dictionary = {"Name": "Harry", "Age": 17}

• Using dict.get():

name = dictionary.get("Name", "Unknown Name")
age = dictionary.get("Age", 0)
print(name)  # Output: Harry
print(age)  # Output: 17

In this example, providing default values ensures that even if the keys "Name" or "Age" are not in the dictionary, reasonable values are returned.

• Using dict[key]:

try:
    name = dictionary["Name"]
except KeyError:
    name = "Unknown Name"

try:
    age = dictionary["Age"]
except KeyError:
    age = 0
print(name)  # Output: Harry
print(age)  # Output: 17

While this method works, it requires you to handle the KeyError manually.

Default Value for None

By default, dict.get() returns None for missing keys. You can also specify your own default value to handle missing keys more gracefully.

Summary

dict.get() is useful for retrieving values from dictionaries while providing a default value if the key doesn't exist. This simplifies code and ensures that invalid keys don't cause errors.

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