Choosing dict.get() Over dict[] in Python

When working with dictionaries in Python we have two main ways to access values: using the square bracket notation (d[s]) and the get method (d.get(s)). This article explores why choosing d.get() over d[s] can lead to more robust and cleaner code unlike d[s], which raises a KeyError when a key is missing, d.get() gracefully returns None or a default value that we specify. This not only simplifies error handling but also reduces the need for extra checks or try-except blocks. By the end of this article, we'll understand how using d.get() can help us write more concise and maintainable Python code. Although both methods retrieve the value associated with a specified key, dict.get(key) is often the preferred choice. Here's why:

1. Handling Missing Keys

Using dict[key] to access a value can raise a KeyError if the key is not present in the dictionary. The dict.get(key) method on the other hand returns None or a specified default value if the key is missing, preventing errors.

# Using dict[key]
d = {'a': 1, 'b': 2}
val = d['c']  # Raises KeyError
print(val)

Output:

KeyError: 'c'

Using dict.get(key):

# Using dict.get(key)
d = {'a': 1, 'b': 2}
val = d.get('c') # Returns None, no KeyError
print(val)

None

2. Providing Default Values

The dict.get(key, default) method allows us to specify a default value that will be returned if the key is not found, this makes the code more robust and easier to read.

# Using dict.get(key, default)
d = {'a': 1, 'b': 2}
val = d.get('c', 0)  # Returns 0, as 'c' is not in the dictionary
print(val)

0

3. Simplifying Conditional Checks

Using dict.get(key) can simplify our code by removing the need for explicit checks for key existence before accessing values.

# Without dict.get(key)
d = {'a': 1, 'b': 2}
if 'c' in d:
    val = d['c']
else:
    val = 0

# Using dict.get(key)
val = d.get('c', 0)  # Simplifies the code
print(val)

0

4. Avoiding Try-Except Blocks

Using dict.get(key) can eliminate the need for try-except blocks to handle missing keys leading to cleaner and more readable code.

# Without dict.get(key)
d = {'a': 1, 'b': 2}
try:
    val = d['c']
except KeyError:
    val = 0

# Using dict.get(key)
val = d.get('c', 0)
print(val)

0