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1. PYTHON PROGRAMMING
IV. Program Components
Engr. Ranel O. Padon

2. PYTHON PROGRAMMING TOPICS
I
• Introduction to Python Programming
II
• Python Basics
III
• Controlling the Program Flow
IV
• Program Components: Functions, Classes, Modules, and Packages
V
• Sequences (List and Tuples), and Dictionaries
VI
• Object-Based Programming: Classes and Objects
VII
• Customizing Classes and Operator Overloading
VIII
• Object-Oriented Programming: Inheritance and Polymorphism
IX
• Randomization Algorithms
X
• Exception Handling and Assertions
XI
• String Manipulation and Regular Expressions
XII
• File Handling and Processing
XIII
• GUI Programming Using Tkinter

3. THE TARGET SCENARIO

4. THE BUILDING BLOCKS

5. DIVISION OF LABOR

6. DIVISION OF LABOR

7. THE ASSEMBLY LINE

8. DIVIDE-AND-CONQUER
every problem can be broken down into smaller/more
manageable sub-problems

9. DIVIDE-AND-CONQUER ALGORITHM
most computer programs that solve real-world problems are
complex/large
the best way to develop and maintain a large program is to
construct it from smaller pieces or components

10. PYTHON PROGRAM COMPONENTS
 functions
 classes
 modules
 collection of functions & classes
 packages
 collection of modules

11. PYTHON PROGRAM COMPONENTS
Function
Package
Class
Module

12. FUNCTIONS
collection or block of statements that you can execute
whenever and wherever you want in the program

13. FUNCTIONS

14. FUNCTIONS

15. WHY FUNCTIONS?
 avoids duplicating code snippets
 saves typing
 easier to change the program later

16. PYTHON MODULES
groups related functions & classes

17. PYTHON MODULES






mathematical calculations
string manipulations
character manipulations
web programming
graphics programming
…

18. PYTHON MODULES
STANDARD LIBRARY
 collection of Python modules
 found in C:Python27Lib folder

19. PYTHON MODULES
STANDARD LIBRARY
* found in C:Python27Lib

20. PYTHON MODULES
STANDARD LIBRARY
 familiarize yourself with the Standard Library
 don’t reinvent the wheel

21. PYTHON PACKAGES
 groups related modules
 code calling in several locations
 prevents name collision

22. PYTHON PACKAGES (site-packages)

23. PYTHON PACKAGE (numpy)

24. PYTHON SUB-PACKAGE (polynomial)
showing the Modules of the polynomial package.

25. PYTHON MODULE (polynomial.py)
showing a part of the content of the polynomial module

26. PYTHON FUNCTIONS
* groups related modules
* code calling in several locations
* prevents name collision

27. PYTHON FUNCTIONS
* groups related modules
* code calling in several locations
* prevents name collision

28. PYTHON FUNCTIONS (math MODULE)
* groups related modules
* code calling in several locations
* prevents name collision

29. PYTHON FUNCTIONS (math MODULE)

30. PYTHON FUNCTIONS (DEFINITION)

31. PYTHON FUNCTIONS (DEFINITION)

32. PYTHON FUNCTIONS (DEFINITION)

33. PYTHON FUNCTIONS (return KEYWORD)

34. PYTHON FUNCTIONS (return KEYWORD)

35. PYTHON FUNCTIONS (return TUPLES)

36. PYTHON FUNCTIONS
def sumDiff(x, y):
return (x+y), (x-y)
sum, diff = sumDiff(2, 3)
print sum
print diff

37. PYTHON FUNCTIONS

38. PYTHON FUNCTIONS (random MODULE)

39. PYTHON FUNCTIONS (random MODULE)

40. PYTHON FUNCTIONS (random MODULE)

41. VARIABLE SCOPE
all variables in a program may not be accessible at all locations
in that program
the scope of a variable determines the portion of the program
where you can access a particular variable

42. VARIABLE SCOPE
variables that are defined inside a function body have a local
scope, and those defined outside have a global scope
inside a function, a local variable takes precedence over a
global variable of the same name
possible workaround:
change the variable names to avoid collision

43. VARIABLE SCOPE

44. VARIABLE SCOPE

45. PYTHON FUNCTIONS (ARGUMENTS)
You can call a function by using the
following types of formal arguments:




Required Arguments
Default Arguments
Keyword Arguments
Variable-Length Arguments

46. PYTHON FUNCTIONS (PARAMS vs ARGS)
Function Parameters
Function Arguments

47. PYTHON FUNCTIONS (ARGUMENTS)
Required/Mandatory Arguments
passed to a function in correct positional order

48. PYTHON FUNCTIONS (ARGUMENTS)
Keyword Arguments
the caller identifies the arguments by the parameter name as
keywords, with/without regard to positional order

49. PYTHON FUNCTIONS (ARGUMENTS)
Default/Optional Arguments
assumes a default value if a value is not provided in the function
call for that argument.

50. PYTHON FUNCTIONS (ARGUMENTS)
Variable-Length Arguments
can handle no-argument, 1-argument, or many-arguments function
calls

51. PYTHON FUNCTIONS (ARGUMENTS)
Combining the Argument Types

52. NAMESPACES
refers to the current snapshot of loaded
names/variables/identifiers/folders
functions must be loaded into the memory before you could call
them, especially when calling external functions/libraries

53. NAMESPACES (Importing a Package)
current snapshot of the default
and imported namespaces

54. NAMESPACES (Importing Packages)

55. NAMESPACES (Importing Functions)

56. NAMESPACES (Importing Functions)

57. NAMESPACES (Built-In Functions)

58. NAMESPACES (Importing All Functions)

59. NAMESPACES (Importing All Functions)

60. NAME BINDING
they are used for better readability, faster coding,
or simply just for convenience

61. NAME BINDING

62. NAME BINDING

63. NAME BINDING

64. NAME BINDING

65. HANDLING MODULES

66. HANDLING MODULES (Error?)

67. HANDLING MODULES (Debug)

68. HANDLING MODULES (Correct Import)

69. HANDLING MODULES (Correct Import)

70. HANDLING MODULES (Alternative)

71. HANDLING MODULES (Will Work)

72. HANDLING MODULES (Will Not Work)
It could not locate the sum() function.

73. HANDLING PACKAGES
The __init__.py files are required to make Python treat the
directories as containing packages

74. HANDLING PACKAGES (The GE file)
The geodetic_engineering.py file/module, located in the
engineering and diliman parent folders/packages.

75. HANDLING PACKAGES (Will Not Work)
The demo.py file importing the geodetic_engineering.py file/module.

76. HANDLING PACKAGES (Will Work)
The demo.py file importing the geodetic_engineering.py file/module.

77. HANDLING PACKAGES (Will Work)
The demo.py file importing the geodetic_engineering.py file/module.

78. HANDLING PACKAGES (Will Work)
The demo.py file importing the geodetic_engineering.py file/module.

79. HANDLING PACKAGES (Will Work)
The demo.py file importing the geodetic_engineering.py file/module.

80. HANDLING PACKAGES (Summary)
IMPORTATION
INVOCATION
import p1.p2.m
p1.p2.m.f1()
from p1.p2 import m
m.f1()
from p1.p2.m import f1
f1()
Where p means package, m means module, f means a function/class.

81. PRACTICE EXERCISE 1
Compute the factorial of a number n:
• n is a number inputted by the user
• make a factorial function and call it to solve
the factorial of n

82. PRACTICE EXERCISE 2
Compute the sum of a number range, say, from a to b, inclusive:
• a, b are numbers inputted by the user
• make a sum_range(a, b) function and call it to solve the
sum of all numbers from a to b, including a and b.

83. Divide-and-Conquer is Powerful!

84. REFERENCES
 Deitel, Deitel, Liperi, and Wiedermann - Python: How to Program (2001).
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