Lists are one of the most commonly used data structures in Python. They are ordered, mutable (changeable), and allow duplicate elements. Lists are defined by placing items inside square brackets [], separated by commas.
Creating a List:
You can create a list by placing a comma-separated sequence of items inside square brackets. Lists can contain elements of different data types, including integers, strings, and even other lists.
Python
# Creating a list of fruits
fruits = ["apple", "banana", "cherry"]
# Lists can contain items of different data types
mixed_list = [1, "apple", True, 3.14]
# Empty list
empty_list = []
Accessing List Items:
You can access list items by referring to the index number, starting from 0 for the first item. Negative indexing allows you to start from the end of the list.
Python
# Accessing list items
print(fruits[0]) # Output: apple
print(fruits[-1]) # Output: cherry
Modifying List Items:
Since lists are mutable, you can change the value of specific items by accessing them through their index.
Python
# Changing the value of an item
fruits[1] = "blueberry"
print(fruits) # Output: ["apple", "blueberry", "cherry"]
Adding Items to a List:
You can add items to a list using methods like append(), insert(), or extend():
Python
# Append an item to the end of the list
fruits.append("date")
print(fruits) # Output: ["apple", "blueberry", "cherry", "date"]
# Insert an item at a specific index
fruits.insert(1, "banana")
print(fruits) # Output: ["apple", "banana", "blueberry", "cherry", "date"]
# Extend the list by appending elements from another list
fruits.extend(["elderberry", "fig"])
print(fruits) # Output: ["apple", "banana", "blueberry", "cherry", "date", "elderberry", "fig"]
Removing Items from a List:
You can remove items from a list using methods like remove(), pop(), or clear():
Python
# Remove a specific item by value
fruits.remove("blueberry")
print(fruits) # Output: ["apple", "banana", "cherry", "date", "elderberry", "fig"]
# Remove an item by index and return it
popped_item = fruits.pop(2)
print(popped_item) # Output: cherry
print(fruits) # Output: ["apple", "banana", "date", "elderberry", "fig"]
# Clear all items from the list
fruits.clear()
print(fruits) # Output: []
List Comprehension:
List comprehension offers a concise way to create lists. It is generally more compact and faster than traditional loops.
Python
# Create a list of squares
squares = [x**2 for x in range(5)]
print(squares) # Output: [0, 1, 4, 9, 16]
Lists are versatile and powerful, allowing you to store and manipulate collections of items easily. Mastering list operations is key to efficient Python programming.
Lists in Python
Python mein lists ek bahut common data structure hain. Ye ordered, mutable (matlab badli ja sakti hain), aur duplicate elements ko allow karti hain. Lists ko square brackets [] ke andar items rakh ke banaya jata hai, jo commas se separate hote hain.
Creating a List:
Aap list ko square brackets ke andar comma-separated items rakh kar bana sakte ho. Lists mein alag-alag data types ke elements ho sakte hain, jaise integers, strings, aur doosri lists bhi.
Python
# Fruits ki ek list bana rahe hain
fruits = ["apple", "banana", "cherry"]
# Lists mein alag-alag data types ke items ho sakte hain
mixed_list = [1, "apple", True, 3.14]
# Empty list
empty_list = []
Accessing List Items:
Aap list ke items ko index number se access kar sakte ho, jisme pehla item 0 index pe hota hai. Negative indexing ka use karke list ke end se access kiya ja sakta hai.
Python
# List ke items ko access karna
print(fruits[0]) # Output: apple
print(fruits[-1]) # Output: cherry
Modifying List Items:
Kyunki lists mutable hoti hain, aap specific items ki value ko unke index ke through change kar sakte ho.
Python
# Kisi item ki value change karna
fruits[1] = "blueberry"
print(fruits) # Output: ["apple", "blueberry", "cherry"]
Adding Items to a List:
Aap append(), insert(), ya extend() methods ka use karke list mein items add kar sakte ho:
Python
# List ke end mein ek item add karo
fruits.append("date")
print(fruits) # Output: ["apple", "blueberry", "cherry", "date"]
# Kisi specific index pe ek item insert karo
fruits.insert(1, "banana")
print(fruits) # Output: ["apple", "banana", "blueberry", "cherry", "date"]
# Ek aur list ke elements ko append karke list extend karo
fruits.extend(["elderberry", "fig"])
print(fruits) # Output: ["apple", "banana", "blueberry", "cherry", "date", "elderberry", "fig"]
Removing Items from a List:
Aap remove(), pop(), ya clear() methods ka use karke list se items remove kar sakte ho:
Python
# Kisi specific item ko remove karo value ke through
fruits.remove("blueberry")
print(fruits) # Output: ["apple", "banana", "cherry", "date", "elderberry", "fig"]
# Index se item ko remove karke return karo
popped_item = fruits.pop(2)
print(popped_item) # Output: cherry
print(fruits) # Output: ["apple", "banana", "date", "elderberry", "fig"]
# List ke saare items ko clear karo
fruits.clear()
print(fruits) # Output: []
List Comprehension:
List comprehension ek concise tareeka hai list banane ka. Ye generally traditional loops se zyada compact aur fast hota hai.
Python
# Squares ki ek list banao
squares = [x**2 for x in range(5)]
print(squares) # Output: [0, 1, 4, 9, 16]
Lists kaafi versatile aur powerful hain, jo aapko items ka collection store karne aur manipulate karne mein asani deti hain. List operations ko samajhna Python programming mein efficient kaam karne ke liye zaroori hai.
Import Links
Here are some useful import links for further reading: