Introduction
So far, you’ve learned about variables, control flow, and
functions. But real-world programs often need to store and organize collections
of data. Python provides powerful built-in data structures for this: lists,
tuples, and dictionaries. In this tutorial, we’ll explore each one with
examples and exercises.
1: Lists — Ordered, Mutable Collections
A list is an ordered collection that can hold multiple
items. Lists are mutable, meaning you can change them after creation.
Code:
fruits =
["apple", "banana", "cherry"]
print(fruits) #
Output: ['apple', 'banana', 'cherry']
print(fruits[0]) #
Output: apple
Adding and Removing Items
Code:
fruits =
["apple", "banana", "cherry"]
print(fruits) # Output: ['apple', 'banana', 'cherry']
fruits.append("orange") #
Add at the end
print(fruits) # Output: ['apple', 'banana', 'cherry',
'orange']
fruits.remove("banana") #
Remove by value
print(fruits) #
Output: ['apple', 'cherry', 'orange']
Iterating Over Lists
Code:
fruits = ["apple", "banana",
"cherry"]
for fruit in fruits:
print(fruit)
Note: Lists are perfect for storing sequences of items you want to modify.
2: Tuples — Ordered, Immutable Collections
A tuple is similar to a list, but immutable — once
created, it cannot be changed.
Code:
coordinates = (10, 20)
print(coordinates[0])
# Output: 10
print(coordinates[1]) # Output: 20
Tuples are useful when you want to ensure data stays constant, like fixed positions or configuration values.
Attempting to modify a tuple will cause an error:
coordinates[0] = 15 #
Error: 'tuple' object does not support item assignment
3: Dictionaries — Key-Value Pairs
A dictionary stores data as key-value pairs. Think of it
like a real dictionary: you look up a word (key) to find its meaning (value).
student = {
"name":
"Deepak",
"age": 30,
"course":
"Python"
}
print(student["name"]) # Output: Deepak
print(student["age"]) # Output: 30
Adding and Updating
student = {
"name":
"Deepak",
"age": 30,
"course":
"Python"
}
print(student)
student["grade"] = "A" # Add new key-value pair
student["age"] = 31
# Update existing value
print(student)
Iterating Over Dictionaries
student = {
"name":
"Deepak",
"age": 30,
"course":
"Python"
}
for key, value in student.items():
print(key,
":", value)
4: Choosing the Right Data Structure
Lists: Use when you need an ordered collection that
can change.
Tuples: Use when you need an ordered collection that must
stay constant.
Dictionaries: Use when you need to map keys to values for
quick lookups.
Mini Exercise
Try this challenge:
·
Create a list of three
cities.
·
Convert it into a tuple.
·
Create a dictionary where
each city is a key, and the value is the population.
·
Print the dictionary in a
readable format.
Hint:
populations = {
"Delhi": 19000000,
"Mumbai": 20000000,
"Bengaluru": 12000000
}
for city, population in populations.items():
print(f"{city}
has a population of {population}.")
Conclusion:
In this tutorial, you learned how to:
·
Use lists for ordered,
mutable collections
·
Use tuples for ordered,
immutable collections
·
Use dictionaries for
key-value mappings
Data structures are the foundation of organizing
information in Python. With these tools, you can manage everything from simple
lists of items to complex structured data.
In the next tutorial, we’ll explore loops with data
structures — how to process collections efficiently and build small projects
like a contact book.