🚀 Day 49/150 – Remove Duplicates from a List in Python

Removing duplicates means keeping only unique elements in a list.

Example:
[1, 2, 2, 3, 4, 4, 5] → [1, 2, 3, 4, 5]

Let’s explore different ways to remove duplicates 👇

🔹 Method 1 – Using set()

numbers = [1, 2, 2, 3, 4, 4, 5] unique = list(set(numbers)) print("Unique List:", unique)
This is the simplest and fastest method.
However, it does not preserve the original order of elements.

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🔹 Method 2 – Using Loop

numbers = [1, 2, 2, 3, 4, 4, 5]

unique = []

for num in numbers:
    if num not in unique:
        unique.append(num)

print("Unique List:", unique)

This method is easy to understand and preserves order, making it great for beginners.

🔹 Method 3 – Using dict.fromkeys()

numbers = [1, 2, 2, 3, 4, 4, 5] unique = list(dict.fromkeys(numbers)) print("Unique List:", unique)

This is a clean and efficient method that also maintains order (Python 3.7+).

🔹 Method 4 – Using List Comprehension
numbers = [1, 2, 2, 3, 4, 4, 5]

unique = []
[unique.append(x) for x in numbers if x not in unique]

print("Unique List:", unique)




This works correctly, but it’s not recommended because list comprehensions are meant for creating lists, not for side effects.



🔹 Output
Unique List: [1, 2, 3, 4, 5]


🔥 Key Takeaways
✔️ Use set() for speed when order doesn’t matter

✔️ Use loops or dict.fromkeys() to preserve order

✔️ Avoid using list comprehension for side effects

✔️ Choose the method based on your requirement