Python Dictionary setdefault()

The syntax of setdefault() is:

dictionary.setdefault(key, default_value)

setdefault() Parameters

The python setdefault() method takes two parameters as arguments:

• key - Key to being searched in the dictionary.
• default_value - The value to be returned in case the key is not found. If not provided, the defalut_value will be None.

Let see some examples of python dictionaries setdefault() method.

Example 1: How to use setdefault() method on python dictionary?

Dogs = {'name' : 'Coco', 'age' : 4}

dog_age = Dogs.setdefault('age')
print('Age of Dog is:', dog_age)

Output:

Age of Dog is: 4

Example 2: How setdefault() works when a key is not in the dictionary?

Dogs = {'name': 'Coco'}

# key is not in the dictionary
color = Dogs.setdefault('color')
print('Dogs = ',Dogs)
print('color = ',color)

# key is not in the dictionary
# default_value is provided
age = Dogs.setdefault('age', 4)
print('Dogs = ',Dogs)
print('age = ',age)

Output:

Dogs =  {'name': 'Coco', 'color': None}
color =  None
Dogs =  {'name': 'Coco', 'color': None, 'age': 4}
age =  4

Rules of setdefault()

• Only returns a result if the given key is present in the dictionary.
• Will return None when the key is not present in the dictionary and default value is not specified.