Collections.UserList in Python
Note: For more information, refer to Python List
Collections.UserList
Python supports a List similar as a container called UserList present in the collections module. This class acts when a wrapper class around the List objects. This class is useful when one wants to create a list of their own with some modified functionality or with some new functionality. It can be considered when a way of adding new behaviors for the list. This class takes a list instance when an argument and simulates a list that is kept in a regular list. The list is accessible by the data property of this class.
Syntax:
collections.UserList([list])
Example 1:
Python3
# Python program to demonstrate# userlistfrom collections import UserListL = [1, 2, 3, 4]# Creating a userlistuserL = UserList(L)print(userL.data)# Creating empty userlistuserL = UserList()print(userL.data) |
Output:
[1, 2, 3, 4] []
The time complexity of this Python program is O(n), where n is the length of the input list L.
The auxiliary space has used by this program is O(n), where n is the length of the input list L.
Python3
# Python program to demonstrate# userlist from collections import UserList # Creating a List where# deletion is not allowedclass MyList(UserList):        # Function to stop deletion    # from List    def remove(self, s = None):        raise RuntimeError("Deletion not allowed")            # Function to stop pop from     # List    def pop(self, s = None):        raise RuntimeError("Deletion not allowed")    # Driver's codeL = MyList([1, 2, 3, 4])print("Original List")# Inserting to List"L.append(5)print("After Insertion")print(L)# Deleting From ListL.remove() |
Output:
Original List After Insertion [1, 2, 3, 4, 5]
Traceback (most recent call last):
File "/home/9399c9e865a7493dce58e88571472d23.py", line 33, in
L.remove()
File "/home/9399c9e865a7493dce58e88571472d23.py", line 15, in remove
raise RuntimeError("Deletion not allowed")
RuntimeError: Deletion not allowed