Python dictionary setdefault() method
By C.Surya VenkatIn this tutorial, we are going to learn setdefault() method in Python with some easy examples. That is most important to many programmers while dealing with a dictionary.
Usually, in Python, while dealing with the “Dictionary” datatype sometimes we require to find whether an element is present in a dictionary or not.
To solve this problem we use a method in Python called “setdefault()” method.
Python setdefault() method
Before starting, first of all, let us know about a dictionary in Python.
Dictionary in Python: A dictionary is a collection datatype that contains elements, usually stored in the form of keys and values. The elements in a dictionary are unordered, unchangeable and indexed.
Representation:
We usually represent a dictionary in Python by using “{}” brackets.
Note:
In the dictionary, values are stored in “key: value” pairs.
setdefault() method:
Syntax:
setdefault(key,value)
Parameters:
key: The element that we want to search in the dictionary.
value: The value that is to be inserted in the dictionary if the key is not found.
Note:
When the value is not specified then by default it assigns to “None”.
Calling:
Because setdefault() is a method, therefore, we use the dot operator “.” to call the setdefault() method.
Return:
The setdefault() method returns THE VALUE OF THE KEY IF IT IS PRESENT IN THE DICTIONARY, else it INSERTS KEY WITH THE SPECIFIED VALUE INTO THE DICTIONARY.
EXAMPLE 1:
#Python code to demonstrate setdefault() method
>>> dict = {"a" : "code","b" : "speedy","c" : "software","d" : "solutions"}
>>> print(dict)
>>> dict.setdefault("c")
OUTPUT:
{'a': 'code', 'b': 'speedy', 'c': 'software', 'd': 'solutions'}
'software'
In the above example by calling the setdefault() method we get the value of key i.e ‘software’.
EXAMPLE 2:
#Python code to demonstrate setdefault() method
>>> dict = {"a" : "code","b" : "speedy","c" : "software","d" : "solutions"}
>>> print(dict)
>>> dict.setdefault("e")
>>> print(dict)
OUTPUT:
{'a': 'code', 'b': 'speedy', 'c': 'software', 'd': 'solutions'}
{'a': 'code', 'b': 'speedy', 'c': 'software', 'd': 'solutions', 'e': None}
In the above example, because the key is not present in the dictionary therefore setdefault() method returns “none”.
EXAMPLE 3:
#Python code to demonstrate setdefault() method
>>> dict = {"a" : "code","b" : "speedy","c" : "software","d" : "solutions"}
>>>print(dict)
>>> dict.setdefault("f","company")
>>> print(dict)
OUTPUT:
{'a': 'code', 'b': 'speedy', 'c': 'software', 'd': 'solutions'}
{'a': 'code', 'b': 'speedy', 'c': 'software', 'd': 'solutions', 'e': None, 'f': 'company'}
In the above example because the key "f" isn't present in the dictionary setdefault() method, therefore, inserts the value "company" into the dictionary.
Finally, I hope that this tutorial was helpful to understand the setdefault() method successfully!!
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