1# Định nghĩa function
2def greet(name):
3    """Chào người dùng - đây là docstring"""
4    return f"Hello, {name}!"
5
6# Gọi function
7message = greet("MinAI")
8print(message)  # Hello, MinAI!
9
10# Function không có return
11def print_info(name, age):
12    print(f"Name: {name}")
13    print(f"Age: {age}")
14    # Tự động return None

1# Default parameters
2def greet(name, greeting="Hello"):
3    return f"{greeting}, {name}!"
4
5greet("Alice")           # "Hello, Alice!"
6greet("Alice", "Hi")     # "Hi, Alice!"
7
8# Keyword arguments
9def create_profile(name, age, city):
10    return {"name": name, "age": age, "city": city}
11
12# Có thể gọi theo bất kỳ thứ tự
13profile = create_profile(age=25, city="Hanoi", name="Bob")
14
15# *args - Nhận nhiều positional arguments
16def sum_all(*args):
17    return sum(args)
18
19sum_all(1, 2, 3, 4, 5)  # 15
20
21# **kwargs - Nhận nhiều keyword arguments
22def build_dict(**kwargs):
23    return kwargs
24
25build_dict(a=1, b=2, c=3)  # {'a': 1, 'b': 2, 'c': 3}
26
27# Kết hợp
28def func(a, b, *args, **kwargs):
29    print(f"a={a}, b={b}")
30    print(f"args={args}")
31    print(f"kwargs={kwargs}")
32
33func(1, 2, 3, 4, x=10, y=20)
34# a=1, b=2
35# args=(3, 4)
36# kwargs={'x': 10, 'y': 20}

1def get_stats(numbers):
2    """Tính các thống kê cơ bản"""
3    return min(numbers), max(numbers), sum(numbers)/len(numbers)
4
5# Unpacking
6min_val, max_val, avg = get_stats([1, 2, 3, 4, 5])
7print(f"Min: {min_val}, Max: {max_val}, Avg: {avg}")
8# Min: 1, Max: 5, Avg: 3.0
9
10# Hoặc nhận tuple
11stats = get_stats([1, 2, 3, 4, 5])
12print(stats)  # (1, 5, 3.0)

1# Cú pháp: lambda arguments: expression
2
3# Function thường
4def square(x):
5    return x ** 2
6
7# Lambda tương đương
8square = lambda x: x ** 2
9
10# Sử dụng
11print(square(5))  # 25
12
13# Lambda với nhiều arguments
14add = lambda x, y: x + y
15print(add(3, 4))  # 7
16
17# Lambda thường dùng với map, filter, sorted
18numbers = [1, 2, 3, 4, 5]
19
20# map - áp dụng function cho từng phần tử
21squares = list(map(lambda x: x**2, numbers))
22# [1, 4, 9, 16, 25]
23
24# filter - lọc phần tử
25evens = list(filter(lambda x: x % 2 == 0, numbers))
26# [2, 4]
27
28# sorted - sắp xếp với key
29students = [
30    {"name": "Alice", "score": 85},
31    {"name": "Bob", "score": 92},
32    {"name": "Charlie", "score": 78}
33]
34sorted_students = sorted(students, key=lambda x: x["score"], reverse=True)
35# Bob (92), Alice (85), Charlie (78)

1def timer(func):
2    """Decorator đo thời gian chạy"""
3    import time
4    def wrapper(*args, **kwargs):
5        start = time.time()
6        result = func(*args, **kwargs)
7        end = time.time()
8        print(f"{func.__name__} took {end-start:.4f} seconds")
9        return result
10    return wrapper
11
12# Sử dụng decorator
13@timer
14def slow_function():
15    import time
16    time.sleep(1)
17    return "Done!"
18
19slow_function()
20# slow_function took 1.0012 seconds

1def repeat(times):
2    """Decorator chạy function nhiều lần"""
3    def decorator(func):
4        def wrapper(*args, **kwargs):
5            for _ in range(times):
6                result = func(*args, **kwargs)
7            return result
8        return wrapper
9    return decorator
10
11@repeat(times=3)
12def say_hello(name):
13    print(f"Hello, {name}!")
14
15say_hello("World")
16# Hello, World!
17# Hello, World!
18# Hello, World!

1from functools import lru_cache
2
3# Caching - Lưu kết quả để không tính lại
4@lru_cache(maxsize=128)
5def fibonacci(n):
6    if n < 2:
7        return n
8    return fibonacci(n-1) + fibonacci(n-2)
9
10print(fibonacci(100))  # Rất nhanh nhờ cache!
11
12# Property decorator
13class Circle:
14    def __init__(self, radius):
15        self._radius = radius
16    
17    @property
18    def radius(self):
19        return self._radius
20    
21    @radius.setter
22    def radius(self, value):
23        if value < 0:
24            raise ValueError("Radius must be positive")
25        self._radius = value
26    
27    @property
28    def area(self):
29        import math
30        return math.pi * self._radius ** 2
31
32circle = Circle(5)
33print(circle.area)  # 78.539...

1# Basic try-except
2try:
3    result = 10 / 0
4except ZeroDivisionError:
5    print("Cannot divide by zero!")
6
7# Multiple exceptions
8try:
9    num = int(input("Enter a number: "))
10    result = 10 / num
11except ValueError:
12    print("Invalid input - not a number!")
13except ZeroDivisionError:
14    print("Cannot divide by zero!")
15
16# Catch all exceptions
17try:
18    risky_operation()
19except Exception as e:
20    print(f"Error occurred: {e}")
21
22# else and finally
23try:
24    file = open("data.txt", "r")
25    content = file.read()
26except FileNotFoundError:
27    print("File not found!")
28else:
29    # Chạy nếu không có lỗi
30    print(f"File content: {content}")
31finally:
32    # Luôn luôn chạy
33    print("Cleanup done")

1def validate_age(age):
2    if age < 0:
3        raise ValueError("Age cannot be negative")
4    if age > 150:
5        raise ValueError("Age seems unrealistic")
6    return True
7
8# Custom Exception
9class InvalidDataError(Exception):
10    """Exception cho dữ liệu không hợp lệ"""
11    def __init__(self, message, error_code=None):
12        super().__init__(message)
13        self.error_code = error_code
14
15def process_data(data):
16    if not data:
17        raise InvalidDataError("Data is empty", error_code=1001)
18    if not isinstance(data, dict):
19        raise InvalidDataError("Data must be dictionary", error_code=1002)
20    return data
21
22# Sử dụng
23try:
24    process_data([])
25except InvalidDataError as e:
26    print(f"Error: {e}, Code: {e.error_code}")

1# File handling với with
2with open("data.txt", "r") as file:
3    content = file.read()
4# File tự động đóng sau khi ra khỏi with block
5
6# Custom context manager
7class Timer:
8    def __enter__(self):
9        import time
10        self.start = time.time()
11        return self
12    
13    def __exit__(self, *args):
14        import time
15        self.end = time.time()
16        print(f"Elapsed: {self.end - self.start:.4f}s")
17
18with Timer():
19    # Code cần đo thời gian
20    sum([i**2 for i in range(1000000)])
21# Elapsed: 0.1234s

1numbers = [1, 2, 3, 4, 5]
2
3# map - transform
4squares = list(map(lambda x: x**2, numbers))
5
6# filter - lọc
7evens = list(filter(lambda x: x % 2 == 0, numbers))
8
9# reduce - aggregate
10from functools import reduce
11total = reduce(lambda x, y: x + y, numbers)  # 15
12
13# zip - kết hợp
14names = ["Alice", "Bob"]
15scores = [85, 90]
16combined = list(zip(names, scores))  # [("Alice", 85), ("Bob", 90)]
17
18# enumerate - index + value
19for idx, val in enumerate(numbers):
20    print(f"{idx}: {val}")
21
22# any, all
23any([False, True, False])   # True (có ít nhất 1 True)
24all([True, True, False])    # False (không phải tất cả True)

1numbers = [3, 1, 4, 1, 5, 9, 2, 6]
2
3len(numbers)      # 8
4sum(numbers)      # 31
5min(numbers)      # 1
6max(numbers)      # 9
7sorted(numbers)   # [1, 1, 2, 3, 4, 5, 6, 9]
8
9# abs, round, pow
10abs(-5)           # 5
11round(3.14159, 2) # 3.14
12pow(2, 10)        # 1024
13
14# isinstance, type
15isinstance(5, int)     # True
16type([1, 2, 3])        # <class 'list'>

1# Import toàn bộ module
2import math
3print(math.sqrt(16))  # 4.0
4
5# Import với alias
6import pandas as pd
7import numpy as np
8
9# Import specific functions
10from math import sqrt, pi
11print(sqrt(16))  # 4.0
12
13# Import all (không khuyến khích)
14from math import *

1# utils.py
2def calculate_mean(numbers):
3    return sum(numbers) / len(numbers)
4
5def calculate_std(numbers):
6    mean = calculate_mean(numbers)
7    variance = sum((x - mean)**2 for x in numbers) / len(numbers)
8    return variance ** 0.5
9
10# main.py
11from utils import calculate_mean, calculate_std
12
13data = [1, 2, 3, 4, 5]
14print(calculate_mean(data))  # 3.0
15print(calculate_std(data))   # 1.414...

1# my_module.py
2def main():
3    print("Running as main script")
4
5def helper():
6    return "Helper function"
7
8# Chỉ chạy khi file được execute trực tiếp
9if __name__ == "__main__":
10    main()
11
12# Khi import: main() không tự động chạy
13# from my_module import helper