1. Principles of Computing – UFCFA3-30-1
Week-8
Python Language
Instructor : Mazhar H Malik
Global College of Engineering and Technology

2. Python Language 1

3. Topics for Today Python Primer Python Introduction
Installation/IDE uses
Lists & its Operations
Dictionary & its Operations
String & its Operations
Control Structure
Looping
Conditions
Data Structure
List
Sets
Dictionary 2

4. Why Python? Python is easy to use
Python typically operates at a much higher level of
abstraction.
Syntax rules are very simple.
Python to take one-fifth the time it would if coded
in C or Java

5. Why Python? Example: – Python is expressive
Expressive in this context means that a single line of Python code can do more than a single line of code in most other languages
Example:
In java
int temp = var1;
var1 = var2;
var2 = temp;
Python
var2, var1 = var1, var2
1/17/2017 1

6. Why Python? Python is readable
one can guess easily what’s happening in code
#Perl version. sub pairwise_sum { my($arg1, $arg2) = ();
@list1
@list2
for($i=0; $i <
$i++) {
$list1[$i] +
$list2[$i]); }
# Python version.
def pairwise_sum(list1, list2): result = []
for i in range(len(list1)): result.append(list1[i] + list2[i])
return result

7. Why Python? Python is complete Python is cross-platform Python is free
Python standard library comes with modules for handling , web pages, databases, operating system calls, GUI development, and more.
Python is cross-platform
Python runs on many different platforms: Windows, Mac, Linux, UNIX, and so on.
Python is free
Python was originally, and continues to be, developed under the open source model, and it’s freely available. You can download and install practically any version of Python and use it to develop software for commercial or personal applications, and you don’t need to pay a dime.

8. Installing Python
Installing Python is a simple matter, regardless of which platform you’re
using. the most recent one can always be found at

9. command-line

10. The IDLE integrated development environment

11. Interactive and Programing Mode
IDE: Integrated Development Environment

12. Comments
For the most part, anything following a # symbol in a Python file is a comment and is disregarded by the language.

13. Variables and assignments

14. del statement
The del statement deletes the variable.

15. Expressions Python supports arithmetic and similar
expressions; these will be familiar to most readers. The following code calculates the average of 3 and 5, leaving the result in the variable z:

16. Strings
You can use single quotes instead of double quotes. The following two lines do the same thing:
x = "Hello, World"
x = 'Hello, World'

17. Numbers
Python offers four kinds of numbers: integers, floats, complex numbers, and Booleans.

18. Built-in numeric functions
Python provides the following number- related functions as part of its core:
abs, divmod, cmp, coerce, float, hex, int,
long, max, min, oct, pow, round

19. Getting input from the user
You can also use the input() function to get input from the user. Use the prompt string you want displayed to the user as input’s parameter:

20. Lists Lists are like arrays
A list in Python is much the same thing as an array in Java or C or any other language. It’s an ordered collection of objects. You create a listd by enclosing
a comma separated
brackets, like so:
Example
x = [1, 2, 3]
list of elements in square

21. List indices
Elements can be extracted from a Python list using a notation like C’s array indexing.
Like C and many other languages, Python starts counting from 0; asking for element 0
if indices are negative numbers, they indicate positions counting from the end of the list, with –1 being the last position in the list, –2 being the second-to-last position, and so forth.

22. List indices
In thelist ["first", "second", "third", "fourth"], you can think of the indices as pointing like this:

23. Slicing in List
enter list[index1:index2] to extract all items including index1 and up to (but not including) index2 into a new list.

24. Slicing in List
When slicing a list, it’s also possible to leave out index1 or index2. Leaving out index1 means “go from the beginning of the list,” and leaving out index2 means “go to the end of the list”:

25. Slicing in List
Omitting both indices makes a new list that goes from the beginning to the end of the original list; that is, it copies the list. This is useful when you wish to make a copy that you can modify, without affecting the original list:

26. Modifying lists
You can use list index notation to modify a list as well as to extract an element from it.

27. Modifying lists
Slice notation can be used here too. Saying something like lista[index1:index2] = listb causes all elements of lista between index1 and index2 to be replaced with the elements in listb. listb can have more or fewer elements than are removed from lista, in which case the length of lista will be altered. You can use slice assignment to do a number of different things, as shown here:

28. Append, Extend
Appending a single element to a list is such a common operation that there’s a special append method to do it:
The extend method is like the append method, except that it
allows you to add one list to another:

29. Insert
insert is used as a method of lists and takes two additional arguments; the first is the index position in the list where the new element should be inserted, and the second is the new element itself:

30. The del statement
The del statement is the preferred method of deleting list items or slices. It doesn’t do anything that can’t be done with slice assignment, but it’s usually easier to remember and easier to read:

31. removes
remove looks for the first instance of a given value in a list and removes that value from the list:

32. Sorting lists
Lists can be sorted using the built-in Python sort method:

33. List membership with the in operator
It’s easy to test if a value is in a list using the in operator, which returns a Boolean value. You can also use the converse, the not in operator:

34. Min/Max
You can use min and max to find the smallest and largest elements in a list

35. List search with index
If you wish to find where in a list a value can be found (rather than wanting to know only if the value is in the list), use the index method.

36. List matches with count
count also searches through a list, looking for a given value, but it returns the number of times that value is found in the list rather than positional information:

37. Summary of list operations

38. Summary of list operations

39. Nested lists
Lists can be nested. One application of this is to represent two-dimensional matrices. The members of these can be referred to using two-dimensional indices. Indices for these work as follows:

40. Strings
strings can be considered sequences of characters which means you can use index or slice notation:

41. The split and join string methods
join takes a list of strings and puts them together to form a single string with the original string between each element.

42. The split and join string methods
split returns a list of substrings in the string
By default, split splits on any whitespace, not just a single space character, but you can also tell it to split on a particular sequence by passing it an optional argument:

43. Modifying strings with list manipulations

44. index
Returns the location of substring in text

45. Excercise
Write a Program that input a name and and print in abbreviated form
Eg. Kamrn Ahmed
K. Ahmed

46. Replace
Replaces the first occurrence with other one.
of substring

47. upper
Convert into upper case

48. Title
Capitalize the string

49. Excercise
Write a Program that input a name convert into capital, lower and upper Case.
Eg. Kamrn ahmed
Kamran Ahmed
KAMRAN AHMED
kamran ahmed

50. Range function

51. Comprehension

52. Looping

53. Exercise
Write a program that print EVEN numbers (2-20)

54. Home-Work
Write a program to generate Fibonacci series

55. Fibonacci series – Home Work

56. While Loop – Table

57. Exercise
Write a program to produce following output

58. For Loop

59. For Loop

60. The for loop with range function
Sometimes you need to loop with explicit indices (to use the position at which values occur in a list). You can use the range command together with the len command on lists to generate a sequence of indices for use by the for loop.

61. For Loop

62. For Loop output?

63. For Loop output?

64. Comprehension

65. String operations

66. Today’s Class Topic Assignments Python Dictionary and Sets
Probabilistic Algorithms (GA)
Research Paper Titled “Genetic
Algorithm
Implementation in Python”
Assignments
Write code of basic Genetic Algorithm in Python with reference of above research paper. Last Date: Two Weeks 65 –

67. Python Dictionary 66

68. Dictionary

69. Dictionary

70. Dictionary

71. Dictionary

72. Dictionary

73. Dictionary

74. Dictionary

75. Accessing Values in Dictionary
Each key is separated from its value by a colon (:), the items are separated by commas, and the whole thing is enclosed in curly braces. An empty dictionary without any items is written with just two curly braces, like this: {}. 74

76. Updating Dictionary
You can update a dictionary by adding a new entry or a key-value pair, modifying an existing entry, or deleting an existing entry as shown below in the simple example 75

77. Updating Dictionary
What about concatenating dictionaries, like we did with lists? There is something similar for dictionaries: the update method update() merges the keys and values of one dictionary into another, overwriting values of the same key: 76

78. Delete Dictionary Elements
you can either remove individual dictionary elements or clear the entire contents of a dictionary. You can also delete entire dictionary in a single operation.
To explicitly remove an entire dictionary, just use the del statement.
Following is a simple example − 77

79. Iterating over a Dictionary78

80. Iterating over a Dictionary79

81. Dictionaries from Lists
Now we will create a dictionary, which assigns a dish to a country, of course according to the common prejudices. For this purpose we need the function zip(). The name zip was well chosen, because the two lists get combined like a zipper. 80

82. Dictionaries from Lists81

83. Sets in Python
The data tpye "set", which is a collection type, has been part of Python since version 2.4. A set contains an unordered collection of unique and immutable objects. The set data type is, as the name implies, a Python implementation of the
sets as they are known
from
sets
mathematics. This explains, why
unlike lists or tuples can't have multiple occurrences of the same element. 82

84. Creating Sets 83

85. Set from List We can pass a list to the built-in set
function, as we can see in the following: 84

86. Frozensets
Frozensets are like sets except that they cannot be changed, i.e. they are immutable: 85

87. Set Operations 86

88. add(element) 87

89. clear 88

90. copy 89

91. difference 90

92. Difference Update 91

93. discard(el) 92

94. remove 93

95. intersection(s) 94

96. issubset() 95

97. issuperset() 96

98. pop 97

99. Useful Modules, Packages and Libraries

100. Useful Modules, Packages and Libraries

101. Useful Modules, Packages and Libraries

102. Useful Modules, Packages and Libraries

103. Useful Modules, Packages and Libraries

104. Useful Modules, Packages and Libraries

105. Useful Modules, Packages and Libraries

106. GUI

107. WxPython

108. Boa Constructor - wxPython GUI Builder

109. Visual Python for 3D graphics

110. Development
Game

111. Plotting

112. Thank You

113. References
112