Python (Chapter 5.1) : Operations "OF" LIST

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Operations of List


We will discuss all the properties of List here. List has all the below methods defined in it. I will suggest to type and execute these codes in your python interpreter as well. I am repeating myself that ALL the methods of LIST are mentioned below. So once we finish this chapter, LIST will be much simpler for you. But you have to execute these 1-2 lines of code in your python interpreter simultaneously. 

1. To declare a list named students

        students=["William","Shreya","David","Amol"]

2. To print a list

  print (students)

  output:

        ['William', 'Shreya', 'David', 'Amol']  

3. To print the datatype of students

        print (type (students))

    output:
            <class ‘list’>




 4. To print the length of the list

        print (len(students))

        output:

               4

5. To print the name of 1^st student

        print (students[0])

        output:

               'William'

6. To print the name of 2^nd student

        print (students[1])

        output:

               'Shreya'

7. To print the name of last student

        print (students[-1])

        output:

               'Amol'

8. To print the name of 2^nd last student

        print (students[-2])

        output:

               'David'

9. To print the last element by the length of list

        print (students[len(students)-1])

        output:

               'Amol'

10. To print the 1st 2 elements

        print (students[0:2])

        output:

               ['Williams', 'Shreya']

11. To print the 2^nd and 3^rd  elements means the elements at position 1 and 2

        print (students[1:3])

        output:

               ['Shreya' , 'David']

12. To print the length of the part of list

        print (len(students[1:]))

        output:

               3

13. To print the elements starting from zero, we can skip the initial zero.

        print (students[:3])

        output:

               ['Williams', 'Shreya' , 'David']

14. To print the elements starting from zero and print every 2nd element , bring a third argument as 2

        print (students[:3:2])

        output:

               ['Williams', 'David']

15. To print the elements starting from zero and print every 2nd element till last , we can skip the middle argument

        print (students[::2])

        output:

               ['Williams', 'David']

16. To print the list after slicing the last 2 elements from back. (remember, slicing the elements from position -1,-2)

        print (students[:-2])

        output:

               [ 'Williams' , 'Shreya' ]

17. To print a range of list after calculating elements from back.(-3:-1 means elements at -3 and -2)

        print (students[-3:-1])

        output:

               [ 'Shreya' , 'David' ]

18. To print a list in reverse order

        print (students[::-1])

        output:

               [ 'Amol' , 'David' , 'Shreya', 'Williams']

19. To print every 2^nd element of a list in reverse order

        print (students[::-2])

        output:

               [ 'Amol' , 'Shreya' ]

20. To insert an element at the last of the list

students.append("Irfan")

print (students[:])

        output:

               ['Williams', 'Shreya', 'David' , 'Amol' , 'Irfan' ]

21. To insert an element at 2^nd position or position 3

students.insert(3,"Roy")

print (students)

        output:

               ['Williams', 'Shreya', 'David' , 'Roy', 'Amol' , 'Irfan' ]

22. To insert multiple element at the last of list

students.extend(["Robert","James","Antenio"])

print (students)

        output:

        ['Williams','Shreya','David','Roy','Amol','Irfan','Robert','James','Antenio']

23. To remove by position, here we are deleting 5^th element

Students.remove(5)

print (students)

        output:

        ['Williams','Shreya','David','Roy','Amol','Robert','James','Antenio']

24. To remove by value, here we are deleting Robert

Students.remove("Robert")

print (students)

        output:

                ['Williams','Shreya','David','Roy','Amol','James','Antenio']

25. To remove element from a position , we can also use POP(), it is similar to REMOVE() . Only difference is , it returns the element after deletion.

print (Students.pop(3))

print (students)

        output:

               'David'

               ['Williams','Shreya','Roy','Amol','James','Antenio']

26. By default POP returns the element from the last (remember, not the latest)

print (Students.pop())

print (students)

        output:

               'Antenio'

               ['Williams','Shreya','Roy','Amol','James']

27. To return the count of the elements in the list, remember the search value is case sensitive

print (Students.count("Roy"))

        output:

               1

28. To return the count of the elements in the list

print (Students.index("Amol"))

        output:

               3

29. To reverse the elements of the list

students.reverse()

print (students)

        output:

               ['James', 'Amol' , 'Roy' ,'Shreya' ,'Williams']           

30. To copy the elements of one list into another

st1=students.copy()

print(st1)

        output:

               ['James', 'Amol' , 'Roy' ,'Shreya' ,'Williams']           

31. To sort the elements of the list

students.sort()

print (students)

        output:

               ['Amol' , 'James', 'Roy' ,'Shreya' ,'Williams']           


       Even we can sort the list in descending order as well. 

students.sort( reverse=true )

print (students)

        output:

               [ 'Williams' ,'Shreya' ,'Roy' ,'James','Amol' ,]           

32. We can clear all the elements of a list

students.clear()

print (students)

        output:

               []         



33. We can create list with elements having different datatype.

S1=[1,"Hi",3.5,"Hello"]

print (S1)

        output:

               [1,'Hi',3.5, 'Hello']



34. We can create a new list even with a another list datatype.

S2=[ 2, ["Raj","Alok"] , ["Bibek"]]

print (S2)

        output:

                [2, ['Raj', 'Alok'], ['Bibek']]

              


35. Print the element inside the sublist.

        print (S2[1][0])

        output:

                Raj

               

36. Append S2 as a new list element at the end of S1

S1.append(S2)

print(S1)                                                                                                                

        output:

               [1, 'Hi', 3.5, 'Hello', [2, ['Raj', 'Alok'], ['Bibek']]]