Common Data Structure Methods

Data structures come with built-in tools called methods.

Methods help you add data, remove data, search data, sort data, and more.

Learning common methods will make your Python work faster and easier.

What Is a Method?

A method is a function attached to an object.

You run it using a dot .

name = "python"
print(name.upper())

Output

PYTHON

Here:

• upper() is a method
• It works on the string stored in name

List Methods

append()

Adds one item to the end.

items = ["Pen", "Book"]
items.append("Bag")

print(items)

Output

['Pen', 'Book', 'Bag']

insert()

Adds an item at a position.

items = ["Pen", "Bag"]
items.insert(1, "Book")

print(items)

Output

['Pen', 'Book', 'Bag']

remove()

Removes by value.

items = ["Pen", "Book", "Bag"]
items.remove("Book")

print(items)

Output

['Pen', 'Bag']

pop()

Removes by position.

items = ["Pen", "Book", "Bag"]
items.pop(0)

print(items)

Output

['Book', 'Bag']

sort()

Sorts the list.

numbers = [3, 1, 2]
numbers.sort()

print(numbers)

Output

[1, 2, 3]

reverse()

Reverses the list.

numbers = [1, 2, 3]
numbers.reverse()

print(numbers)

Output

[3, 2, 1]

Dictionary Methods

get()

Reads a value safely.

user = {"name": "Tom"}

print(user.get("name"))
print(user.get("age"))

Output

Tom
None

keys()

Shows all keys.

print(user.keys())

Output

dict_keys(['name'])

values()

Shows all values.

print(user.values())

Output

dict_values(['Tom'])

items()

Shows key-value pairs.

print(user.items())

Output

dict_items([('name', 'Tom')])

pop()

Removes by key.

user.pop("name")
print(user)

Output

{}

Set Methods

add()

Adds one item.

tags = {"python"}
tags.add("coding")

print(tags)

update()

Adds many items.

tags.update(["course", "learn"])

print(tags)

remove()

Removes an item.

tags.remove("coding")

print(tags)

discard()

Safe remove.

tags.discard("missing")
print(tags)

String Methods

upper()

text = "hello"
print(text.upper())

Output

HELLO

lower()

print(text.lower())

Output

hello

title()

print(text.title())

Output

Hello

replace()

print(text.replace("hello", "hi"))

Output

hi

split()

words = "learn python now"
print(words.split())

Output

['learn', 'python', 'now']

Why Methods Matter

Methods save time and make code cleaner.

Instead of building everything from scratch, Python gives ready-made tools.

Code Along

cities = ["Toronto", "New York"]
cities.append("Chicago")
cities.sort()

print(cities)

Output

['Chicago', 'New York', 'Toronto']

Mini Challenge

Build a data tool.

Steps:

• Create a list:
  3, 1, 2
• Sort it
• Add 4
• Create a dictionary:
  name: Tom
• Print the keys
• Create a string:
  hello world
• Print it in uppercase

Expected output:

[1, 2, 3, 4]
dict_keys(['name'])
HELLO WORLD

Real World Use Case

Programs use methods every day for text cleaning, updating records, sorting products, and managing data.

Quiz

1. What is a method?
2. Which symbol is used to call a method?
3. Which list method sorts data?
4. Which dictionary method returns all keys?

Assignment

Create your own examples using one list method, one dictionary method, and one string method.

Summary

You learned common methods for lists, dictionaries, sets, and strings that help manage data quickly and cleanly.