🚀 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

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🚀 Day 48/150 – Count Even and Odd Numbers in a List in Python

Counting even and odd numbers in a list helps you practice loops, conditions, and list handling.

 Even numbers are divisible by 2
 Odd numbers are not divisible by 2

Example:
[1, 2, 3, 4, 5] → Even = 2, Odd = 3

Let’s explore different ways 👇

🔹 Method 1 – Using for Loop

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

even = 0
odd = 0

for num in numbers:
    if num % 2 == 0:
        even += 1
    else:
        odd += 1

print("Even:", even)
print("Odd:", odd)






✅ Most common method.

🔹 Method 2 – Taking User Input

numbers = list(map(int, input("Enter numbers: ").split()))

even = odd = 0

for num in numbers:
    if num % 2 == 0:
        even += 1
    else:
        odd += 1

print("Even:", even)
print("Odd:", odd)






✅ Dynamic input.

🔹 Method 3 – Using List Comprehension

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

even = len([num for num in numbers if num % 2 == 0])
odd = len([num for num in numbers if num % 2 != 0])

print("Even:", even)
print("Odd:", odd)

✅ Clean and Pythonic.

🔹 Method 4 – Using while Loop

numbers = [1, 2, 3, 4, 5] i = 0 even = odd = 0 while i < len(numbers): if numbers[i] % 2 == 0: even += 1 else: odd += 1 i += 1 print("Even:", even) print("Odd:", odd)

✅ Loop practice.

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🚀 Day 47/150 – Average of List Elements in Python

 

Finding the average (mean) of a list means adding all elements and dividing by the total number of elements.

Formula:
Average = Sum of elements / Number of elements

Example:
[2, 4, 6, 8] → Average = (2+4+6+8)/4 = 5.0

Let’s explore different ways to calculate average 👇

🔹 Method 1 – Using sum() and len()

✅ Easiest and most recommended method.

numbers = [2, 4, 6, 8] avg = sum(numbers) / len(numbers) print("Average:", avg)

✅ Easiest and most recommended method.

🔹 Method 2 – Using for Loop

numbers = [2, 4, 6, 8]

total = 0

for num in numbers:
    total += num

avg = total / len(numbers)

print("Average:", avg)











✅ Good for understanding logic.

🔹 Method 3 – Taking User Input
numbers = list(map(int, input("Enter numbers: ").split()))

avg = sum(numbers) / len(numbers)

print("Average:", avg)





✅ Dynamic input from user.

🔹 Method 4 – Using while Loop
numbers = [2, 4, 6, 8]

i = 0
total = 0

while i < len(numbers):
    total += numbers[i]
    i += 1

avg = total / len(numbers)

print("Average:", avg)







✅ Alternative looping method.


🔹 Method 5 – Using Function
def average(lst):
    return sum(lst) / len(lst)

print(average([2, 4, 6, 8]))



✅ Clean and reusable.

🔹 Output
Average: 5.0

🔥 Key Takeaways
✔️ Use sum() and len() for simplicity

✔️ Average = total / count

✔️ Loops help build logic

✔️ Handle empty list to avoid division error

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