Lecture notes ENGG1810

ENG1810 Notes
Lecture 2

Lists

● Definition: Lists are mutable, ordered collections of items, allowing duplicates.
● Examples and Operations:
○ Creating and accessing lists:
computer = ['imac', 'alienware', 'inspiron', 'blade']
print(computer[1]) # Output: alienware

○ Adding items:
computer.append('macbook') # Adds at the end
computer.insert(1, 'macbook') # Inserts at index 1

○ Removing items:
computer.remove('inspiron') # Removes 'inspiron'
computer.pop(3) # Removes the fourth item

○ Modifying lists:
computer[3] = 'razer_blade' # Changes 'blade' to 'razer_blade'
Tuples

● Definition: Tuples are immutable, ordered collections that allow duplicate values.
● Operations:
○ Accessing tuples:
my_family = ('mother', 'father', 'sister', 'me')
print(my_family[2]) # Output: sister

○ Modifying tuples (indirectly by converting to a list):
temp_list = list(my_family)
temp_list.append('brother')
my_family = tuple(temp_list)
Sets

● Definition: Sets are unordered, unindexed collections that do not allow duplicates.
● Operations:
○ Adding and removing items:


my_family = {'mother', 'father', 'sister', 'me'}
my_family.add('uncle')
my_family.remove('sister')

,Dictionaries

● Definition: Dictionaries store key-value pairs and are mutable and ordered (as of python
3.7).
● Examples:
○ Creating and accessing dictionaries:
computer = {'brand': 'Apple', 'model': 'iMac', 'year': 2007}
print(computer['model']) # Output: iMac

○ Modifying dictionaries:
computer['year'] = 2010 # Updates the year
computer['color'] = 'silver' # Adds a new key-value pair


Basics of Control Flow
● Control flow in programming refers to the direction in which the program executes. In
Python, this is primarily managed through conditional statements and loops. This lecture
focuses on conditional statements which allow the program to react differently depending
on the input or other data.
Conditional Statements
Conditional statements are the backbone of decision making in Python. They execute a certain
block of code based on a condition. The primary statements used are:

1. if Statement:
○ The if statement is used to test a condition and execute a block of code if the
condition is true.
○ Syntax:
if condition:
# execute this block

○ Example:
if weather == 'sunny':
print("Let's go outside!")

2. else Statement:
○ The else statement follows an if statement and is executed if the if statement’s
condition is false.
○ Syntax:
if condition:
# execute this block
else:
# execute this block

○ Example:

, if weather == 'sunny':
print("Let's go outside!")
else:
print("We might need an umbrella.")

3. elif (else if) Statement:
○ The elif statement is used to check multiple expressions for TRUE and execute a
block of code as soon as one of the conditions evaluates to TRUE.
○ Unlike else, there can be multiple elif blocks following an if.
○ Syntax:
if condition1:
# execute block 1
elif condition2:
# execute block 2
else:
# execute block 3

○ Example:
if weather == 'sunny':
print("Let's go outside!")
elif weather == 'rainy':
print("We need an umbrella.")
else:
print("It's a pleasant day.")

, Lecture 3
While Loops

● A while loop in Python repeatedly executes a target statement as long as a given
condition is true. Here’s how you structure a while loop:
○ while <condition>:
# Execute these actions

● Example: Counting Race Finishers Imagine a scenario where athletes are finishing a
race, and we want to print their finish positions as they cross the line:
○ person = 0
while person < 100:
person += 1
print(person)
● This code will print numbers 1 through 100, simulating athletes finishing from 1st to
100th place.
For Loops

● A for loop is used for iterating over a collection (like a list, tuple, set, or dictionary) or an
iterator. The basic syntax of a for loop is:
● for variable in collection:
# Execute actions




● Example: Iterating Over a List of Students
● students = ['Caren Han', 'Henry Weld', 'Annie Sun', 'Lilian Hunt']
for student in students:
print(student)

● This will print each student's name from the list.