Page 345 - Computer Science Class 11 With Functions
P. 345

●  lst.remove(element): The method remove(element) searches for the first instance of the element
              in the list lst and removes it. If an element is not found in lst, the method remove throws a ValueError.
             >>> lst = [10, 20, 30, 10, 50, 20, 60, 20, 30, 55]
             >>> lst.remove(20)
             >>> lst
                 [10, 30, 10, 50, 20, 60, 20, 30, 55]
             >>> lst.remove(66)
                 Traceback (most recent call last):
                   File "<pyshell#7>", line 1, in <module>
                     lst.remove(66)
                 ValueError: list.remove(x): x not in list
            ●  lst.pop(index):  The  method  removes  the  element  from  the  specified  index and  returns  the element
              removed from the list. If the index is omitted, the rightmost element is returned. For example,
             >>> lst = [10, 20, 30, 10, 50, 20, 60, 20, 30, 55]
             >>> lst.pop(3)
                 10
             >>> lst
                 [10, 20, 30, 50, 20, 60, 20, 30, 55]
             >>> lst.pop()
                 55
             >>> lst
                 [10, 20, 30, 50, 20, 60, 20, 30]
            ●  del statement: The del statement can also be used to remove an element from the list by specifying its index.

             >>> lst = [10, 20, 30, 10, 50, 20, 60, 20, 30, 55]
             >>> del lst[3]
             >>> lst
                 [10, 20, 30, 50, 20, 60, 20, 30, 55]

                  Delete a Slice: You can also use the del statement to remove a slice of elements from the list.

                  myList = [10, 20, 30, 40, 50]
                  del myList[1:4] # Removes elements at index 1, 2, and 3 (20, 30, 40)
                  print(myList) # Output: [10, 50]
                  Delete Entire List: If you want to completely remove the entire list and free up the memory it occupies, you can use
                  the del statement without specifying an index.
                  myList = [10, 20, 30]
                  del myList # Deletes the entire list
                  # Now myList is not defined and will raise an error if used


            13.6.1 Creating a Sorted List

            The function sorted  returns a sorted list comprising the elements of the list passed as argument, but without
            modifying it.

             >>> lst = ['Physics', 'Chemistry', 'Maths', 'Computer Sc.']
             >>> sorted(lst)
                 ['Chemistry', 'Computer Sc.', 'Maths', 'Physics']
             >>> lst
                 ['Physics', 'Chemistry', 'Maths', 'Computer Sc.']
            13.6.2 Quick Programming Question

            Write a function to count the frequency of each element in a list. Make use of it to write a program that accepts a list
            of integers and displays the frequency of each element in the list.




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