Chapter 8: Collections and String Manipulation

8.1 Chapter Overview

In Python, collections are used to store multiple values in a single variable, while string manipulation is used to process and control text data. These two skills are very important for developing real-world applications such as student records systems, attendance systems, course registration systems, report generation tools, chatbot applications, and data cleaning programs.

This chapter combines collection data types and string manipulation so learners can understand how to store, organize, search, update, format, and display data professionally.

8.2 Chapter Objectives

• Understand the purpose of collection data types in Python.
• Create and manage lists, tuples, dictionaries, and sets.
• Use loops to process collection items.
• Understand the purpose of string manipulation.
• Apply common string methods such as upper(), lower(), title(), replace(), split(), and strip().
• Use strings and collections together in practical programs.
• Develop simple applications for student, course, and text processing tasks.

Learning Outcomes

• Differentiate between list, tuple, dictionary, and set.
• Store and process multiple values using Python collections.
• Clean and format text using Python string methods.
• Create practical Python applications using collections and strings.

8.3 Introduction to Python Collections

A collection is a data type that stores more than one value. Instead of creating many separate variables, programmers can group related values together.

8.4 Lists

A list is an ordered and changeable collection. Lists are suitable when data needs to be updated, added, removed, or processed repeatedly.

Creating a List

courses = ["Python", "AI", "Data Science", "Cyber Security"]

print(courses)

Accessing List Items

courses = ["Python", "AI", "Data Science"]

print(courses[0])
print(courses[1])

Adding and Removing Items

courses = ["Python", "AI"]

courses.append("Data Science")
courses.remove("AI")

print(courses)

8.5 Tuples

A tuple is similar to a list, but it cannot be changed after creation. Tuples are useful for fixed information such as course codes, centre details, months, or weekdays.

course_codes = ("CPP101", "AI201", "DS301")

print(course_codes)
print(course_codes[0])

8.6 Dictionaries

A dictionary stores data in key-value pairs. Dictionaries are excellent for structured records such as student profiles, employee details, course information, and product records.

Creating a Dictionary

student = {
    "name": "Amin",
    "age": 20,
    "course": "Certified Python Programmer"
}

print(student)

Accessing Dictionary Values

print(student["name"])
print(student["course"])

Updating Dictionary Values

student["course"] = "AI Application Development"
student["email"] = "amin@example.com"

print(student)

8.7 Sets

A set stores unique values only. It is useful when duplicate data should be removed automatically.

skills = {"Python", "AI", "Python", "Data Science"}

print(skills)

The duplicate value Python appears only once in the set.

Set Operations

group_a = {"Python", "AI", "Excel"}
group_b = {"Python", "Data Science", "Power BI"}

print(group_a.union(group_b))
print(group_a.intersection(group_b))

8.8 Introduction to String Manipulation

String manipulation means working with text data. In Python, a string is a sequence of characters enclosed inside single quotes or double quotes.

student_name = "Amin"
course = "Python Programming"

print(student_name)
print(course)

8.9 String Indexing and Slicing

Strings can be accessed using index numbers. Python indexing starts from 0.

Indexing

course = "Python"

print(course[0])
print(course[1])

Slicing

course = "Python Programming"

print(course[0:6])
print(course[7:18])

8.10 Common String Methods

Example

message = " welcome to pdtc python course "

print(message.upper())
print(message.lower())
print(message.title())
print(message.strip())

8.11 String Concatenation and Formatting

Concatenation means joining strings together. Python also supports f-strings for professional formatting.

Concatenation

first_name = "Amin"
last_name = "Rahman"

full_name = first_name + " " + last_name

print(full_name)

f-String Formatting

name = "Amin"
course = "Python"

print(f"Student {name} is enrolled in {course}.")

8.12 Using split() with Collections

The split() method is very useful because it converts a string into a list.

skills_text = "Python,AI,Data Science,Cyber Security"

skills_list = skills_text.split(",")

print(skills_list)

8.13 Practical Example: Student Profile Application

This example uses a dictionary for student details, a list for skills, and string methods to clean and format input.

student_name = input("Enter student name: ").strip().title()
course = input("Enter course name: ").strip().title()
skills_text = input("Enter skills separated by comma: ")

skills = skills_text.split(",")

student = {
    "name": student_name,
    "course": course,
    "skills": skills
}

print("----- Student Profile -----")
print("Name:", student["name"])
print("Course:", student["course"])
print("Skills:", student["skills"])

8.14 Practical Example: Remove Duplicate Skills

This example uses a list and set together to remove duplicate skill names.

skills = ["Python", "AI", "Python", "Excel", "AI"]

unique_skills = set(skills)

print(unique_skills)

8.15 Common Beginner Mistakes

8.16 Hands-On Practice

8.17 Final Assessment Quiz

Answer the following questions. Correct Answer = +1 Mark Wrong Answer = -0.5 Mark

Final Practical Assessment

Develop an interactive Python program named student_skills_profile.py. The program must ask for student name, course name and skills separated by commas. It must clean and format the name and course, convert skills into a list, remove duplicate skills using a set, and display a clear student profile.

8.18 Chapter Summary

In this chapter, learners studied Python collections and string manipulation. Collections help store and manage multiple values, while string manipulation helps process text data. Together, these skills allow developers to build more practical and interactive Python applications.