Untitled

Introduction to Programming with Python

• Course Code: UGC 1201 - Computer Literacy II
• Lecturer: Lenandlar Singh
• Date: March 18, 2026

Objectives

• At the end of this lecture, students should be able to:
  • Create and use lists
  • Create and use loops
  • Use loops to process lists

Python Lists

• Definition of a List: A list is a kind of collection that allows us to put many values in a single "variable".
  • This is useful because it enables us to carry many values around in one convenient package.
  • Examples:
  • friends = ['Joseph', 'Glenn', 'Sally']
  • carryon = ['socks', 'shirt', 'perfume']

Characteristics of Python Lists

• Versatile Data Type: Lists in Python can store different data types and are defined using square brackets with values separated by commas.
  • Examples:
  • list1 = ['physics', 'chemistry', 1997, 2000]
  • list2 = [1, 2, 3, 4, 5]
  • list3 = ['a', 'b', 'c', 'd']

Built-in Functions and Lists

• Python provides several built-in functions that work with lists as parameters.
• Examples of Built-in Functions:
  • To illustrate:
    python >>> nums = [3, 41, 12, 9, 74, 15] >>> print(len(nums)) # Output: 6 >>> print(max(nums)) # Output: 74 >>> print(min(nums)) # Output: 3 >>> print(sum(nums)) # Output: 154 >>> print(sum(nums) / len(nums)) # Output: 25

Visualising a List Data Structure

• A list can be visualized as follows:
  • Indices: 0 1 2 …
  • Values: 12 21 34
  • The elements of a list can be of any type, e.g.:
  • Index 0: "first"
  • Index 1: 21.5
  • Index 2: True

Accessing List Elements

• Lists use square brackets to access elements.
  • Example: For a list my_list:
    python my_list = [12, 21, 34]
  • The first element can be accessed with my_list[0], and the second with my_list[1].

Creating and Printing Lists

• Lists are created using square brackets, with elements separated by commas.
• Examples:
  • Creating a list: my_list = [12, 21, 34]
  • Creating an empty list can be done by:
  • my_list = []
  • my_list = list()

Printing a List

• Lists can be printed using the print() function:
  python my_list = [5, 2, 7, 4, 3, 8, 0, 1, 9, 6, -3] print(my_list) # Output: [5, 2, 7, 4, 3, 8, 0, 1, 9, 6, -3]
• The length of a list can be obtained using len():
  python number_of_elements = len(my_list) print(number_of_elements) # Output: 11

Iterating Through a List

• To visit each element in a list, a for loop can be used: python my_list = ['No', 'keyboard', 'detected.', 'Press', 'F1', 'to', 'continue'] for element in my_list: print(element)
  • Output:
    • No
    • keyboard
    • detected.
    • Press
    • F1
    • to
    • continue

Processing Lists

• Example of Counting Elements:
  python num = [1, 2, 3, 5, 3, 6, 7, 8, 4, 8] count = 0 for items in num: if items > 5: count += 1 print(count, "items greater than 5") # Output: (number of items greater than 5)

Adding to a List

• Lists can be appended to using append().
• Example:
  python numbers = [22, 300, 400, 440, 650] for i in range(5): print(numbers[i]) numbers.append(i) for i in range(len(numbers)): print(numbers[i])

Basic Search in a List

• Example of Searching:
  python numbers = [22, 300, 400, 440, 650] searchTerm = int(input('Enter search value: ')) if searchTerm in numbers: print('Search term found')

Loops and Iteration in Python

• Definition of Iteration/Loop: This describes repeating code execution until a condition or exit point is met.
• Types of Loops:
  • For Loop: Used for iterating over a sequence (list, tuple, dictionary, set, or string).
  • While Loop

Examples of For Loops

• Example with Input:

  person = input('Enter your name: ')
  for i in range(5):
      print('Hello', person)
  

• Example of Iterating Over a List:

  fruits = ['apple', 'banana', 'cherry']
  for x in fruits:
      print(x)
  

• Example of Iterating with Range:
  python for i in range(5): print('i is', i)

The range() Function

• The range() function allows looping through a set number of times.
  • It returns a sequence of numbers starting from 0 by default, incrementing by 1 by default, and ending at a specified number.
  • Important Note: range(6) produces values 0 to 5, not 0 to 6.
  • You can specify starting values, e.g. range(2, 6) means values from 2 to 5.

Generating Random Numbers

• Example of Generating Random Numbers:
  • A program that generates a list of 5 random numbers from 1 to 9, which replaces initial values in the list:
    python numbers = [0, 0, 0, 0, 0] # Code that generates random numbers goes here.
  • A program that generates a list of 100 random numbers from 1 to 9.

Homework Assignment

• Write a program in Python that:
  • Collects a list of n numbers from the user via the keyboard and calculates how many numbers are greater than the average of all the numbers.

End of Lecture