An unordered collection of data values that are used to store data values like a map is known as Dictionary in Python. Unlike other Data Types that hold only a single value as an element, Dictionary holds key:value pair. Key-value is provided in the dictionary to make it more optimized.
Note: For more information, refer to Python Dictionary
Collections.UserDict
Python supports a dictionary like a container called UserDict present in the collections module. This class acts as a wrapper class around the dictionary objects. This class is useful when one wants to create a dictionary of their own with some modified functionality or with some new functionality. It can be considered as a way of adding new behaviors to the dictionary. This class takes a dictionary instance as an argument and simulates a dictionary that is kept in a regular dictionary. The dictionary is accessible by the data attribute of this class.
Syntax:
collections.UserDict([initialdata])
Example 1:
Python3
# Python program to demonstrate# userdictfrom collections import UserDictd = {'a':1, 'b': 2, 'c': 3}# Creating an UserDictuserD = UserDict(d)print(userD.data)# Creating an empty UserDictuserD = UserDict()print(userD.data) |
Output:
{'a': 1, 'b': 2, 'c': 3}
{}
Example 2: Let’s create a class inheriting from UserDict to implement a customized dictionary.
Python3
# Python program to demonstrate# userdict from collections import UserDict # Creating a Dictionary where# deletion is not allowedclass MyDict(UserDict): # Function to stop deletion # from dictionary def __del__(self): raise RuntimeError("Deletion not allowed") # Function to stop pop from # dictionary def pop(self, s = None): raise RuntimeError("Deletion not allowed") # Function to stop popitem # from Dictionary def popitem(self, s = None): raise RuntimeError("Deletion not allowed") # Driver's coded = MyDict({'a':1, 'b': 2, 'c': 3})print("Original Dictionary")print(d)d.pop(1) |
Output:
Original Dictionary
{'a': 1, 'c': 3, 'b': 2}
Traceback (most recent call last):
File "/home/3ce2f334f5d25a3e24d10d567c705ce6.py", line 35, in
d.pop(1)
File "/home/3ce2f334f5d25a3e24d10d567c705ce6.py", line 20, in pop
raise RuntimeError("Deletion not allowed")
RuntimeError: Deletion not allowed
Exception ignored in:
Traceback (most recent call last):
File "/home/3ce2f334f5d25a3e24d10d567c705ce6.py", line 15, in __del__
RuntimeError: Deletion not allowed
