Python dict.get() Method

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Summary: When working with Python dictionaries, in some cases you may want to access a specific value of a certain item, this is where the dict.get() method comes in handy.

Definition: Python’s dict.get() method expects a key argument. If the specified key is in the dictionary, the method will output the value associated with the key.

Syntax of dict.get() Method

Method Declaration of dict.get():

dict.get(key, optional_value)

The two parameters of dict.get():

  • Key: The key that the dict.get() method searches for in the dictionary.
  • Optional Value: The optional_value is the value output, if the key is not found in the dictionary, the value defaults to None if optional_value isn’t specified.

Output Value of dict.get():

The dict.get() method returns the associated value of the specified key if the key is in the dictionary, otherwise, the default value None or the optional_value that was passed as an argument to the dictionary gets returned.

Basic Exampleof dict.get() Method

grades_dict = {'programming': 83, 'math': 85, 'science': 80}
print(grades_dict.get('programming'))
# 83

Accessing Nested Dictionary Key Values

Here’s how you accidentally define a dictionary with three identical keys:

# Define nested dictionary:
employee_dict = {'id_1': {'name': 'bob', 'age': 20, 'profession': 'programmer'},
                 'id_2': {'name': 'tammy', 'age': 25, 'profession': 'engineer'},
                 'id_3': {'name': 'dylan', 'age': 30, 'profession': 'nurse'}}

print(employee_dict)

Output:

{'id_1': {'name': 'bob', 'age': 20, 'profession': 'programmer'}, 
 'id_2': {'name': 'tammy', 'age': 25, 'profession': 'engineer'}, 
 'id_3': {'name': 'dylan', 'age': 30, 'profession': 'nurse'}}

This code snippet declares a regular dictionary along with three nested dictionaries, each dictionary can then be accessed by its corresponding key.

 
# How to access the elements of a nested dictionary:
# list employee names:


id1_employee = employee_dict.get('id_1', {}).get('name')
id2_employee = employee_dict.get('id_2', {}).get('name')
id3_employee = employee_dict.get('id_3', {}).get('name')


print(id1_employee)
# bob

print(id2_employee)
# tammy

print(id3_employee)
# dylan

Difference dict.get() and dict[key] when Accessing Dictionary Elements

# Empty Dictionary Example
empty_dict = {}


# Applying dict.get() method to an empty dictionary:
print(empty_dict.get('key'))
# None

Now, let’s try to get a key from an empty dictionary using the standard square bracket method to index a non-existent key:

# Applying dict[] to an empty dictionary.
# This results in a keyError being returned:
print(empty_dict['key'])

This results in the following error message that could’ve been prevented with dict.get():

Traceback (most recent call last):
  File "C:\Users\xcent\Desktop\code.py", line 11, in <module>
    print(empty_dict['key'])
KeyError: 'key'