Python Lists

Chapter 3 • Python
Chapter 3 • Python

Python Lists

Python ki sabse useful data structure — List! Multiple items ek jagah store karo, access karo, modify karo!

8 Topics
11 Methods
10 MCQs
30+ Examples

What are Python Lists?

📋 List ek ordered, mutable collection hai jisme aap multiple items ek variable mein store kar sakte ho. Ye Python ki sabse versatile data structure hai!

Simple samjho: List ek dabba hai jisme aap bahut saari cheezein rakh sakte ho — numbers, names, ya kuch bhi! Aur aap kabhi bhi koi item add, remove ya change kar sakte ho.

📦 Ordered

Items jis order mein daale, usi order mein rahte hain

✏️ Mutable

Items add, remove, change — sab kuch kar sakte ho

🔢 Indexed

Har item ka ek number (index) hota hai — 0 se shuru

🎨 Mixed Types

Ek list mein numbers, strings, booleans — sab rakh sakte ho

📏 Dynamic Size

List chhoti-badi ho sakti hai — fixed size nahi hai

python
# List banane ka tarika — square brackets [] use karo
fruits = ["apple", "banana", "cherry", "orange"]
print(fruits)  # ['apple', 'banana', 'cherry', 'orange']

# List mein kitne items hain?
print(len(fruits))  # 4

Types of Python Lists

🗂️ Python mein alag-alag type ki lists bana sakte ho — empty, numbers, strings, mixed, ya nested (list ke andar list)!
python
# 1. Empty List — khaali list
empty = []
print(empty)           # []

# 2. Integer List — sirf numbers
numbers = [1, 2, 3, 4, 5]
print(numbers)         # [1, 2, 3, 4, 5]

# 3. Float List — decimal numbers
prices = [10.5, 20.3, 30.7]
print(prices)          # [10.5, 20.3, 30.7]

# 4. String List — text items
names = ["Rahul", "Priya", "Amit"]
print(names)           # ['Rahul', 'Priya', 'Amit']

# 5. Mixed List — sab kuch mix!
mixed = [1, "Hello", 3.14, True, None]
print(mixed)           # [1, 'Hello', 3.14, True, None]

# 6. Nested List — list ke andar list!
matrix = [[1,2,3], [4,5,6], [7,8,9]]
print(matrix[0])       # [1, 2, 3] (pehli row)
print(matrix[1][2])    # 6 (doosri row, teesra item)

List Kaise Banaye?

🛠️ Python mein list banane ke 3 tarike hain — direct values se, list() function se, ya list comprehension se.

1. Direct Values De Kar

python
# Sabse simple tarika — [] mein values likho
fruits = ["apple", "banana", "cherry"]
numbers = [10, 20, 30, 40, 50]

2. list() Function Se

python
# String se list banao — har character alag item ban jaayega
letters = list("Python")
print(letters)  # ['P', 'y', 't', 'h', 'o', 'n']

# range() se numbers ki list banao
nums = list(range(1, 6))
print(nums)     # [1, 2, 3, 4, 5]

# Tuple se list banao
my_tuple = (10, 20, 30)
my_list = list(my_tuple)
print(my_list)  # [10, 20, 30]

3. List Comprehension — Ek Line Mein! ⭐

python
# Squares nikalo 1 se 5 tak — ek hi line mein!
squares = [x**2 for x in range(1, 6)]
print(squares)  # [1, 4, 9, 16, 25]

# Sirf even numbers filter karo
evens = [x for x in range(1, 11) if x % 2 == 0]
print(evens)    # [2, 4, 6, 8, 10]

# Names ko uppercase mein convert karo
names = ["rahul", "priya", "amit"]
upper = [n.upper() for n in names]
print(upper)    # ['RAHUL', 'PRIYA', 'AMIT']
💡 List comprehension bahut powerful hai — for loop + if condition ek hi line mein! Interviews mein bhi poochha jaata hai.

List Items Access Kaise Kare?

👆 List ke items ko index se access karte hain. Python mein index 0 se shuru hota hai. Negative index se end se access kar sakte ho!
python
fruits = ["apple", "banana", "cherry", "orange", "mango"]
#  Index:    0        1         2        3        4
# Neg idx:  -5       -4        -3       -2       -1

# Positive index — shuru se count karo
print(fruits[0])    # apple  (pehla item)
print(fruits[2])    # cherry (teesra item)

# Negative index — end se count karo
print(fruits[-1])   # mango  (last item)
print(fruits[-2])   # orange (second last)

# ❌ Index out of range — ye error dega!
# print(fruits[10])  # IndexError!
📝 Yaad rakho: Index hamesha 0 se shuru hota hai! Pehla item = index 0, doosra = index 1, aur aige aise hi.

List Slicing

✂️ Slicing se list ka ek hissa (portion) nikal sakte ho. Format: list[start:stop:step] — start se shuru, stop se pehle ruk jaao!
python
nums = [10, 20, 30, 40, 50, 60, 70, 80, 90]

# Basic slicing — [start:stop] (stop excluded!)
print(nums[2:5])     # [30, 40, 50] (index 2, 3, 4)

# Start se leke — [:stop]
print(nums[:4])      # [10, 20, 30, 40] (shuru se 3 tak)

# Kisi index se end tak — [start:]
print(nums[5:])      # [60, 70, 80, 90] (5 se end tak)

# Step ke saath — [start:stop:step]
print(nums[0:8:2])   # [10, 30, 50, 70] (har doosra item)

# Reverse karo! — [::-1]
print(nums[::-1])    # [90, 80, 70, 60, 50, 40, 30, 20, 10]

# Last 3 items
print(nums[-3:])     # [70, 80, 90]

List Traverse Kaise Kare?

🔄 Traversing matlab list ke har ek item ko ek-ek karke access karna. 4 tarike hain:

1. Simple for Loop

python
fruits = ["🍎 Apple", "🍌 Banana", "🍒 Cherry"]

for fruit in fruits:
    print(fruit)
# 🍎 Apple
# 🍌 Banana
# 🍒 Cherry

2. Index ke Saath (range + len)

python
fruits = ["Apple", "Banana", "Cherry"]

for i in range(len(fruits)):
    print(f"Index {i}: {fruits[i]}")
# Index 0: Apple
# Index 1: Banana
# Index 2: Cherry

3. enumerate() — Best Tarika! ⭐

python
fruits = ["Apple", "Banana", "Cherry"]

for index, fruit in enumerate(fruits):
    print(f"{index}. {fruit}")
# 0. Apple
# 1. Banana
# 2. Cherry
💡 enumerate() sabse clean tarika hai jab aapko index aur value dono chahiye!

4. while Loop

python
fruits = ["Apple", "Banana", "Cherry"]
i = 0
while i < len(fruits):
    print(fruits[i])
    i += 1

List Operations

⚙️ Lists par + (jodo), * (repeat karo), aur in (check karo) operations kar sakte ho!
python
# ➕ Concatenation — Do lists jodo
list1 = [1, 2, 3]
list2 = [4, 5, 6]
combined = list1 + list2
print(combined)  # [1, 2, 3, 4, 5, 6]

# ✖️ Repetition — List repeat karo
repeat = [0] * 5
print(repeat)    # [0, 0, 0, 0, 0]

hello = ["Hi"] * 3
print(hello)     # ['Hi', 'Hi', 'Hi']

# 🔍 Membership — Check karo item hai ya nahi
fruits = ["apple", "banana", "cherry"]
print("banana" in fruits)      # True ✅
print("grape" in fruits)       # False ❌
print("grape" not in fruits)   # True ✅

# 📏 Length
print(len(fruits))  # 3

# 🔢 Min, Max, Sum
nums = [10, 5, 20, 15, 3]
print(min(nums))    # 3
print(max(nums))    # 20
print(sum(nums))    # 53

List Methods — Complete Guide

🧰 Python Lists ke paas bahut saare built-in methods hain. Ye methods se aap items add, remove, sort, reverse — sab kuch kar sakte ho!
append(item)— End mein ek item add karo
python
fruits = ["apple", "banana"]
fruits.append("cherry")       # End mein add
print(fruits)  # ['apple', 'banana', 'cherry']
extend(list)— Doosri list ke saare items add karo
python
fruits = ["apple", "banana"]
more = ["cherry", "orange"]
fruits.extend(more)           # Saare items add
print(fruits)  # ['apple', 'banana', 'cherry', 'orange']
insert(index, item)— Kisi specific position par item daalo
python
fruits = ["apple", "cherry"]
fruits.insert(1, "banana")    # Index 1 par daalo
print(fruits)  # ['apple', 'banana', 'cherry']
remove(value)— Pehli matching value hatao
python
fruits = ["apple", "banana", "cherry", "banana"]
fruits.remove("banana")       # Pehla "banana" hatega
print(fruits)  # ['apple', 'cherry', 'banana']
pop(index)— Index se item nikalo aur wapas karo
python
fruits = ["apple", "banana", "cherry"]
removed = fruits.pop(1)       # Index 1 ka item nikalo
print(removed)  # banana
print(fruits)   # ['apple', 'cherry']

last = fruits.pop()           # Bina index = last item
print(last)     # cherry
clear()— Saare items hatao — list khaali karo
python
fruits = ["apple", "banana", "cherry"]
fruits.clear()
print(fruits)  # []  (khaali!)
sort()— Items ko order mein lagao
python
nums = [5, 2, 8, 1, 9, 3]
nums.sort()                   # Chhote se bade
print(nums)    # [1, 2, 3, 5, 8, 9]

nums.sort(reverse=True)       # Bade se chhote
print(nums)    # [9, 8, 5, 3, 2, 1]
reverse()— Items ko ulta karo
python
fruits = ["apple", "banana", "cherry"]
fruits.reverse()
print(fruits)  # ['cherry', 'banana', 'apple']
copy()— List ki copy banao
python
original = [1, 2, 3]
copy_list = original.copy()
copy_list.append(4)           # Copy mein add karo
print(original)   # [1, 2, 3]  (original safe!)
print(copy_list)  # [1, 2, 3, 4]
index(value)— Item ka index number batao
python
fruits = ["apple", "banana", "cherry"]
pos = fruits.index("banana")
print(pos)  # 1
count(value)— Item kitni baar hai — count karo
python
nums = [1, 2, 3, 2, 4, 2, 5]
print(nums.count(2))  # 3 (teen baar hai!)

MCQ Quiz — Test Your Knowledge!

10 important MCQs — Python Lists ke concepts test karo! 📋

1

Python List mein elements ka order maintain hota hai ya nahi?

2

List mein elements change kar sakte hain ya nahi?

3

fruits = ["apple", "banana", "cherry"] fruits[1] ka output kya hoga?

4

fruits[-1] kya return karega?

5

append() aur extend() mein kya fark hai?

6

nums = [1,2,3] nums.insert(1, 10) print(nums) ka output?

7

pop() aur remove() mein kya fark hai?

8

nums = [3,1,4,1,5] nums.sort() print(nums) ka output?

9

List slicing mein nums[1:4] kya return karega? nums = [10,20,30,40,50]

10

List comprehension kya hai?

Practice Questions — Khud Karo! 💪

Python Lists Practice Set 1
Q1

दी गई सूची ["Guava", "Apple", "Banana", "Orange", "Pomegranate"] को उल्टी क्रम में प्रिंट करें।

Print the list in reverse order.

Q2

एक खाली सूची बनाइए और उसमें उपयोगकर्ता से 5 संख्याएँ इनपुट लेकर जोड़िए। इसके बाद सूची के सभी तत्वों को प्रिंट करें।

Create an empty list and take 5 numbers as input from the user. Then print all elements.

Q3

दी गई सूची [10, 20, 30, 40, 50] से एक नई सूची बनाइए जिसमें सभी तत्वों को दुगुना (double) किया गया हो।

Create a new list from [10, 20, 30, 40, 50] where each element is doubled.

Q4

दी गई सूची [1,2,3,4,5] का योग (sum) और औसत (average) निकालिए।

Find the sum and average of the list [1,2,3,4,5].

Q5

दी गई सूची [5,10,15,20,25] से एक नई सूची बनाइए जिसमें केवल odd numbers शामिल हों।

From [5,10,15,20,25], create a new list containing only odd numbers.

Q6

दी गई सूची [10,20,30,40,50] से दूसरे और चौथे तत्व को हटाकर नई सूची प्रिंट करें।

From [10,20,30,40,50], remove the second and fourth elements and print the new list.

Q7

दी गई सूची [1,2,3,4,5,6,7,8,9,10] से एक नई सूची बनाइए जिसमें केवल वे तत्व हों जो 3 से विभाजित होते हों।

From [1,2,3,4,5,6,7,8,9,10], create a new list containing only elements divisible by 3.

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