The setdefault()method is used to retrieve a value from a dictionary given its key. If an item with the given key does not exist in the dictionary, it adds it and sets a given value for it.
The syntax is as shown below:
d.setdefault(key, value = None)
| key | The key whose associated value is to be retrieved |
| value | The value to be set if the item with the given key does not exist. It defaults to None. |
If an item of the given key exists, its value is returned. Otherwise, the key with the specified value is added to the dictionary and the value is returned.
d = {
‘Tokyo’: ‘Japan’,
‘Ottawa’: ‘Canada’,
‘Kigali’: ‘Rwanda’
}
value = d.setdefault(‘Kigali’)
print(value)
In the above example, we used the setdefault()method with a key that exist in the dictionary, ‘Kigali’. The value associated with the key is returned which is ‘Rwanda’.
Consider the following example:
d = {
‘Tokyo’: ‘Japan’,
‘Ottawa’: ‘Canada’,
‘Kigali’: ‘Rwanda’
}
value = d.setdefault(‘Manilla’)
print(value)
print(d)
In the above example, the given key, ‘Manilla’ does not exist in the dictionary. Thesetdefault() method adds an item with the key and sets a default value of Noneto it because we did not specify another value.
with a default value given
d = {
‘Tokyo’: ‘Japan’,
‘Ottawa’: ‘Canada’,
‘Kigali’: ‘Rwanda’
}
value = d.setdefault(‘Manilla’, ‘Philippines’)
print(value)
print(d)
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dict.update() method in Python
items(), keys() and values() methods in Python dictionary
dict.fromkeys() method in Python
