This document provides an introduction to Python programming unit 2 which covers lists, tuples, and dictionaries. Lists allow ordered sets of values accessed by index and can be modified. Tuples are similar to lists but immutable. Dictionaries store elements as key-value pairs that can be accessed by key. Common operations for each include accessing elements, determining length, membership testing, slicing, and built-in methods. Tuples can group data and be used as return values or in nested structures. Dictionaries allow creation and modification of elements through operations and methods.

1. Introduction to Python
Programming Unit 2

2. Contents:
⚫ Lists: List values, Accessing elements, List length, List
membership, List operations, List slices, Lists are mutable, List
deletion, Objects and references, Aliasing, Cloning lists, Lists and
for loops, List parameters, List methods, Pure functions and
modifiers, Functions that produce lists, Strings and lists, list and
range, Nested lists, Matrices.
⚫ Tuples are used for grouping data, Tuple assignment, Tuples as
return values, Composability of Data Structures.
⚫ Dictionaries: Dictionary operations, dictionary methods, aliasing
and copying.

3. LIST
⚫A list is an ordered set of values, where each
value is identified by an index
⚫The values that make up a list are called its
elements.
⚫Also called as sequences

4. LIST VALUES
⚫Ways to create a new list
⚫enclose the elements in square brackets [ ]:
Eg1 [10, 20, 30, 40]
Eg2 ["spam", "bungee", "swallow"]
Eg3 ["hello", 2.7, 5]

5. LIST VALUES
⚫ Lists that contain consecutive integers:
⚫ Empty list it is denoted [].

6. ACCESSING ELEMENTS

7. ACCESSING ELEMENTS
If you try to read or write an
element that does not exist, you
get a runtime error:

8. ACCESSING ELEMENTS
⚫If an index has a negative value, it counts
backward from the end of the list:

9. Using Loops

10. LIST LENGTH
⚫The function len returns the length of a list

11. LIST within another LIST
⚫The function len returns the length of a list

12. List membership
⚫in is a boolean operator that tests membership in
a sequence.

13. List operations
⚫The + operator concatenates lists

14. List operations
⚫Similarly, the * operator repeats a list a given
number of times

15. List slices

16. Lists are mutable
⚫lists are mutable, which means we can
change their elements.

17. List deletion

18. Objects and values

19. Objects and values

20. Aliasing

21. Cloning lists
If we want to modify a list and also keep a
copy of the original

22. Cloning lists
If we want to modify a list and also keep a
copy of the original

23. List parameters

24. Nested lists

25. Matrices
Nested lists are often used to
represent matrices

26. Strings and lists

27. Strings and lists- delimiter

28. Strings and lists- join

29. List Methods

30. List Methods
1. append()
syntax
list.append (element)
['Mathematics', 'chemistry', 1997, 2000, 20544]

31. List Methods
insert()
syntax
list.insert(position, element)
['Mathematics', 'chemistry', 10087,
1997, 2000]

32. List Methods
sum()
syntax
sum(List)

33. List Methods
Length()
syntax
len(list_name)
10

34. List Methods
reverse()
1

35. List Methods
Sort( )

36. Tuples

37. Tuple
⚫A tuple that is similar to a list except that it is
immutable.
⚫Syntactically, a tuple is a comma-separated list
of values:

38. Tuple
⚫To create a tuple with a single element, we
have to include the final comma:
>>> t1 = (’a’,)
• Without the comma, Python treats (’a’) as a
string in parentheses:

39. Tuple
If we try to modify one of the elements of
the tuple, we get an error:

40. Tuple packing and unpacking
Tuple packing is nothing but the creation of
tuple, whereas tuple unpacking means to extract
tuple values and store them in individual
variables.

41. Tuple assignment

42. Tuple assignment

43. Tuples as return values
⚫Functions can return tuples as return values

44. Composability of Data Structures
⚫Tuples items can themselves be other tuples.

45. Dictionary

46. Dictionaries
⚫In a dictionary, the indices are called keys,
so the elements are called key-value pairs.
⚫One way to create a dictionary is to start
with the empty dictionary and add elements.
⚫The empty dictionary is denoted {}

47. Dictionaries

48. Dictionaries
Another way to create a
dictionary
print(len(Subjects)
)

49. Dictionary operations
1. The del statement removes a key-
value pair from a dictionary
2.
print(len(Subjects))

50. Dictionary methods
▪ A method is similar to a function, it
takes arguments and returns a value
but the syntax is different.
▪ print(Subjects.keys())
dict_keys([2, 3, 4])

51. Dictionary methods
▪ The items method returns both, in the
form of a list of tuples—one for each
key-value pair:
print(Subjects.items())
dict_items([(2, 'Physics'), (3,
'Electronics'), (4, 'Python')])

52. Dictionary methods
▪ the method has key takes a key and
returns true (1) if the key appears in
the dictionary:

53. Aliasing and copying
▪ Whenever two variables refer to the same object,
changes to one affect the other.
▪ If you want to modify a dictionary and keep a
copy of the original, use the copy method.
▪ ISEM and Subjects refer to the same object
▪ Copied creates a new copy of Subjects