top 5 most used data structures in Python

Here are the top 5 most used data structures in Python, with explanations and examples 👇

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🥇 1. List

✅ Dynamic array that can store elements of any type.

• Mutable (can be changed)
• Ordered

# Create a list
fruits = ["apple", "banana", "cherry"]

# Access and modify
print(fruits[0])         # apple
fruits.append("mango")   # add element
fruits.remove("banana")  # remove element

print(fruits)            # ['apple', 'cherry', 'mango']

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🥈 2. Tuple

✅ Immutable version of list — once created, can’t be changed.

• Useful for fixed data, like coordinates or config constants.
• Faster than lists.

# Create a tuple
point = (10, 20)

# Access elements
print(point[0])  # 10

# You cannot modify a tuple
# point[0] = 15  ❌ (Error)

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🥉 3. Dictionary (HashMap)

✅ Key–value store, very similar to JavaScript objects or Java HashMaps.

• Unordered (before Python 3.7), now insertion ordered
• Mutable

# Create a dictionary
person = {"name": "Alice", "age": 25}

# Access or update
print(person["name"])       # Alice
person["city"] = "Sydney"   # Add new key
print("age" in person)      # True

# Iterate
for key, value in person.items():
    print(key, value)

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🏅 4. Set

✅ Unordered collection of unique elements.

• Removes duplicates automatically
• Useful for membership testing and set operations.

# Create a set
nums = {1, 2, 3, 2, 1}
print(nums)  # {1, 2, 3}

# Add or remove
nums.add(4)
nums.remove(2)

# Set operations
a = {1, 2, 3}
b = {3, 4, 5}
print(a | b)  # Union: {1, 2, 3, 4, 5}
print(a & b)  # Intersection: {3}

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🎖️ 5. Queue / Deque

✅ For FIFO (First-In, First-Out) or LIFO operations. Python’s collections.deque is faster than list for queue operations.

from collections import deque

queue = deque(["A", "B", "C"])
queue.append("D")    # Enqueue
print(queue.popleft())  # Dequeue -> A
print(queue)            # deque(['B', 'C', 'D'])

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⚡ Summary Table

Data Structure	Ordered	Mutable	Allows Duplicates	Typical Use
List	✅ Yes	✅ Yes	✅ Yes	General storage, iteration
Tuple	✅ Yes	❌ No	✅ Yes	Fixed data (e.g., coordinates)
Dictionary	✅ Yes	✅ Yes	🔑 Keys unique	Key–value mapping
Set	❌ No	✅ Yes	❌ No	Unique elements, membership
Deque	✅ Yes	✅ Yes	✅ Yes	Queues, fast append/pop

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