Writing Python Lists

A-Z of Data Science Part-1

A-Z of Data Science Part-2

❤️ Learning Path for ML

🗓️ Python Basics You Should Know 🐍

✅ 1. Variables & Data Types 
Variables store data. Data types show what kind of data it is.

# String (text)
name = "Alice"

# Integer (whole number)
age = 25

# Float (decimal)
height = 5.6

# Boolean (True/False)
is_student = True

🔹 Use type() to check data type:

print(type(name))  # <class 'str'>

✅ 2. Lists and Tuples
⦁ List = changeable collection

fruits = ["apple", "banana", "cherry"]
print(fruits)  # banana
fruits.append("orange")  # add item

⦁ Tuple = fixed collection (cannot change items)

colors = ("red", "green", "blue")
print(colors)  # red

✅ 3. Dictionaries 
Store data as key-value pairs.

person = {
  "name": "John",
  "age": 22,
  "city": "Seoul"
}
print(person["name"])  # John

✅ 4. Conditional Statements (if-else) 
Make decisions.

age = 20
if age >= 18:
    print("Adult")
else:
    print("Minor")

🔹 Use elif for multiple conditions:

if age < 13:
    print("Child")
elif age < 18:
    print("Teenager")
else:
    print("Adult")

✅ 5. Loops 
Repeat code.

⦁ For Loop – fixed repeats

for i in range(3):
    print("Hello", i)

⦁ While Loop – repeats while true

count = 1
while count <= 3:
    print("Count is", count)
    count += 1

✅ 6. Functions 
Reusable code blocks.

def greet(name):
    print("Hello", name)

greet("Alice")  # Hello Alice

🔹 Return result:

def add(a, b):
    return a + b

print(add(3, 5))  # 8

✅ 7. Input / Output 
Get user input and show messages.

name = input("Enter your name: ")
print("Hi", name)

🧪 Mini Projects

1. Number Guessing Game

import random
num = random.randint(1, 10)
guess = int(input("Guess a number (1-10): "))
if guess == num:
    print("Correct!")
else:
    print("Wrong, number was", num)

2. To-Do List

todo = []
todo.append("Buy milk")
todo.append("Study Python")
print(todo)

🛠️ Recommended Tools
⦁ Google Colab (online)
⦁ Jupyter Notebook
⦁ Python IDLE or VS Code

💡 Practice a bit daily, start simple, and focus on basics — they matter most!

Data Science Roadmap: https://news.1rj.ru/str/datasciencefun/3730

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4 ways to copy a list in Python

In Python, there are several ways to make a copy of a list. But it is important to understand the difference between a shallow copy and a deep copy.

original = [1, 2, [3, 4]]

# 1. Slice (shallow copy)
copy1 = original[:]

# 2. .copy() method (shallow copy)
copy2 = original.copy()

# 3. Using list() (shallow copy)
copy3 = list(original)

# 4. deepcopy (deep copy)
import copy
copy4 = copy.deepcopy(original)

Now let's check the difference between shallow and deep copy:

original[2].append(5)
print(copy1)
# [1, 2, [3, 4, 5]] — nested list changed!
print(copy4)
# [1, 2, [3, 4]] — unchanged