Lists in Python

1. Lists in Python
Md. Shafiuzzaman
Lecturer, Dept. of CSE, JUST

2. Why list?

3. The List Data Type
• A list is a value that contains multiple values in an ordered sequence
• A list value looks like this: ['cat', 'bat', 'rat', 'elephant']
• Values inside the list are also called items

4. Getting Individual Values in a List with Indexes

5. Getting Individual Values in a List with Indexes
• Python will give you an IndexError error message if you use an index
that exceeds the number of values in your list value
• Indexes can be only integer values, not floats

6. Lists of lists

7. Negative Indexes

8. Getting Sublists with Slices
• A slice can get several values from a list, in the form of a new list

9. Getting Sublists with Slices

10. Getting a List’s Length

11. Changing Values in a List with Indexes

12. List Concatenation and List Replication

13. Removing Values from Lists

14. Using for Loops with Lists

15. Using for Loops with Lists

16. Using for Loops with Lists

17. Exercise

18. Solution

19. The in and not in Operators
• You can determine whether a value is or isn’t in a list with the in and
not in operators.

20. The in and not in Operators

21. Multiple Assignment

22. Augmented Assignment Operators

23. Methods
• A method is the same thing as a function, except it is “called on” a
value
• Example: spam.index('hello')
• Each data type has its own set of methods
• List data type has several methods for finding, adding, removing, and
otherwise manipulating values in a list

24. Finding a Value in a List with the index()
Method

25. Finding a Value in a List with the index()
Method
• When there are duplicates of the value in the list, the index of its first
appearance is returned

26. Adding Values to Lists: append()

27. Adding Values to Lists: insert()

28. Removing Values from Lists with remove()

29. Removing Values from Lists with remove()

30. Removing Values from Lists with remove()

31. del statement vs remove()
• del statement is good to use when you know the index of the value
you want to remove from the list
• remove() method is good when you know the value you want to
remove from the list

32. Practice Projects: Comma Code

33. Sorting the Values in a List with the sort()
Method

34. Sorting the Values in a List with the sort()
Method

35. Sorting the Values in a List with the sort()
Method
• sort() method sorts the list in place; don’t try to capture the return
value by writing code like spam = spam.sort()
• you cannot sort lists that have both number values and string values
in them

36. Sorting the Values in a List with the sort()
Method
sort() uses “ASCIIbetical order” rather than actual alphabetical
order for sorting strings

37. Sort the values in regular alphabetical order

38. List-like Types: Strings

39. List-like Types: Strings
• Store your name in name variable and type the following code

40. Lists vs String
• List -> mutable: It can have values added, removed, or changed
• String -> immutable: It cannot be changed

41. “mutate” a string: slicing and concatenation

42. The Tuple Data Type
• Tuples are immutable
• Tuples cannot have their values modified, appended, or removed

44. Converting Types with the list() and tuple()
Functions

45. References

46. References

47. Passing References

48. Copy Module’s copy() and deepcopy()
Functions