Thực Hành Python Cơ Bản

1# Công thức: F = C × 9/5 + 32
2def celsius_to_fahrenheit(c):
3    return c * 9/5 + 32
4
5def fahrenheit_to_celsius(f):
6    return (f - 32) * 5/9
7
8# Test
9temps_c = [0, 25, 37, 100]
10for c in temps_c:
11    f = celsius_to_fahrenheit(c)
12    print(f"{c}°C = {f:.1f}°F")
13
14# Output:
15# 0°C = 32.0°F
16# 25°C = 77.0°F
17# 37°C = 98.6°F
18# 100°C = 212.0°F

1def calculate_bmi(weight, height):
2    bmi = weight / (height ** 2)
3    
4    if bmi < 18.5:
5        category = "Gầy"
6    elif bmi < 25:
7        category = "Bình thường"
8    elif bmi < 30:
9        category = "Thừa cân"
10    else:
11        category = "Béo phì"
12    
13    return bmi, category
14
15# Test
16weight, height = 70, 1.75
17bmi, cat = calculate_bmi(weight, height)
18print(f"BMI: {bmi:.1f} → {cat}")
19# BMI: 22.9 → Bình thường

1for i in range(1, 31):
2    if i % 15 == 0:
3        print("FizzBuzz")
4    elif i % 3 == 0:
5        print("Fizz")
6    elif i % 5 == 0:
7        print("Buzz")
8    else:
9        print(i)
10
11# List comprehension version
12result = ["FizzBuzz" if i%15==0 else "Fizz" if i%3==0 
13          else "Buzz" if i%5==0 else str(i) for i in range(1, 31)]

1def is_prime(n):
2    if n < 2:
3        return False
4    for i in range(2, int(n**0.5) + 1):
5        if n % i == 0:
6            return False
7    return True
8
9primes = [n for n in range(2, 101) if is_prime(n)]
10print(f"Có {len(primes)} số nguyên tố: {primes}")
11# Có 25 số nguyên tố: [2, 3, 5, 7, 11, 13, ...]

1def validate_password(password):
2    errors = []
3    
4    if len(password) < 8:
5        errors.append("Cần ít nhất 8 ký tự")
6    if not any(c.isupper() for c in password):
7        errors.append("Cần ít nhất 1 chữ hoa")
8    if not any(c.islower() for c in password):
9        errors.append("Cần ít nhất 1 chữ thường")
10    if not any(c.isdigit() for c in password):
11        errors.append("Cần ít nhất 1 chữ số")
12    if not any(c in "!@#$%^&*" for c in password):
13        errors.append("Cần ít nhất 1 ký tự đặc biệt (!@#$%^&*)")
14    
15    if errors:
16        return False, errors
17    return True, ["Mật khẩu hợp lệ! ✅"]
18
19# Test
20passwords = ["abc", "Hello123", "Str0ng@Pass"]
21for pw in passwords:
22    valid, messages = validate_password(pw)
23    print(f"\n'{pw}': {'✅' if valid else '❌'}")
24    for msg in messages:
25        print(f"  - {msg}")

1# Tam giác
2n = 5
3for i in range(1, n + 1):
4    print(" " * (n - i) + "*" * (2*i - 1))
5#     *
6#    ***
7#   *****
8#  *******
9# *********
10
11# Kim cương
12for i in range(1, n + 1):
13    print(" " * (n - i) + "*" * (2*i - 1))
14for i in range(n - 1, 0, -1):
15    print(" " * (n - i) + "*" * (2*i - 1))

1def word_counter(text):
2    words = text.lower().split()
3    count = {}
4    for word in words:
5        word = word.strip(".,!?")  # Bỏ dấu câu
6        count[word] = count.get(word, 0) + 1
7    
8    # Sắp xếp theo tần suất giảm dần
9    sorted_words = sorted(count.items(), key=lambda x: x[1], reverse=True)
10    return sorted_words
11
12text = "the cat sat on the mat the cat likes the mat"
13result = word_counter(text)
14for word, freq in result:
15    print(f"  '{word}': {freq} lần")
16# 'the': 4 lần, 'cat': 2 lần, 'mat': 2 lần, ...

1def create_grade_manager():
2    students = {}
3    
4    def add_student(name, scores):
5        students[name] = scores
6    
7    def get_average(name):
8        if name not in students:
9            return None
10        scores = students[name]
11        return sum(scores) / len(scores)
12    
13    def get_ranking():
14        averages = {name: sum(s)/len(s) for name, s in students.items()}
15        return sorted(averages.items(), key=lambda x: x[1], reverse=True)
16    
17    def summary():
18        ranking = get_ranking()
19        print(f"\n{'Xếp hạng':^40}")
20        print("-" * 40)
21        for rank, (name, avg) in enumerate(ranking, 1):
22            grade = "A" if avg >= 9 else "B" if avg >= 8 else "C" if avg >= 7 else "D"
23            print(f"  #{rank} {name:<15} TB: {avg:.1f} ({grade})")
24    
25    return add_student, get_average, get_ranking, summary
26
27# Sử dụng
28add, avg, rank, summary = create_grade_manager()
29add("Alice", [9, 8.5, 9.5, 10])
30add("Bob", [7, 8, 7.5, 8])
31add("Charlie", [10, 9, 9.5, 9])
32summary()

1# Khách hàng theo kênh
2online = {"Alice", "Bob", "Charlie", "Diana", "Eve"}
3store = {"Bob", "Frank", "Charlie", "Grace"}
4mobile = {"Alice", "Charlie", "Henry", "Diana"}
5
6# Phân tích
7print(f"Mua online: {len(online)} người")
8print(f"Mua cửa hàng: {len(store)} người")
9print(f"Mua mobile: {len(mobile)} người")
10
11# Mua tất cả kênh
12all_channels = online & store & mobile
13print(f"\nMua cả 3 kênh: {all_channels}")  # {'Charlie'}
14
15# Chỉ mua online
16only_online = online - store - mobile
17print(f"Chỉ online: {only_online}")  # {'Eve'}
18
19# Tổng khách hàng unique
20total = online | store | mobile
21print(f"Tổng unique: {len(total)} người")  # 8

1def flatten(lst):
2    """Flatten list lồng nhau bất kỳ"""
3    result = []
4    for item in lst:
5        if isinstance(item, list):
6            result.extend(flatten(item))  # Đệ quy
7        else:
8            result.append(item)
9    return result
10
11# Test
12nested = [1, [2, 3], [4, [5, 6]], [7, [8, [9]]]]
13print(flatten(nested))
14# [1, 2, 3, 4, 5, 6, 7, 8, 9]
15
16# One-liner (chỉ 1 cấp)
17simple = [[1,2], [3,4], [5]]
18flat = [x for sublist in simple for x in sublist]
19# [1, 2, 3, 4, 5]

1import time
2from functools import wraps
3
4def log(func):
5    """Decorator ghi log mỗi lần gọi function"""
6    @wraps(func)
7    def wrapper(*args, **kwargs):
8        args_str = ", ".join(map(str, args))
9        kwargs_str = ", ".join(f"{k}={v}" for k, v in kwargs.items())
10        all_args = ", ".join(filter(None, [args_str, kwargs_str]))
11        print(f"📝 Calling {func.__name__}({all_args})")
12        result = func(*args, **kwargs)
13        print(f"✅ {func.__name__} returned: {result}")
14        return result
15    return wrapper
16
17def retry(max_attempts=3, delay=1):
18    """Decorator thử lại khi gặp lỗi"""
19    def decorator(func):
20        @wraps(func)
21        def wrapper(*args, **kwargs):
22            for attempt in range(1, max_attempts + 1):
23                try:
24                    return func(*args, **kwargs)
25                except Exception as e:
26                    print(f"⚠️ Attempt {attempt}/{max_attempts} failed: {e}")
27                    if attempt < max_attempts:
28                        time.sleep(delay)
29            raise Exception(f"Failed after {max_attempts} attempts")
30        return wrapper
31    return decorator
32
33# Test
34@log
35def add(a, b):
36    return a + b
37
38@retry(max_attempts=3, delay=0.5)
39def risky_operation():
40    import random
41    if random.random() < 0.7:
42        raise ConnectionError("Network timeout")
43    return "Success!"
44
45add(3, 5)
46risky_operation()

1def load_data(raw_data):
2    """Bước 1: Parse raw data"""
3    return [row.split(",") for row in raw_data.strip().split("\n")]
4
5def clean_data(data):
6    """Bước 2: Clean & validate"""
7    header = data[0]
8    cleaned = []
9    for row in data[1:]:
10        if len(row) == len(header) and all(cell.strip() for cell in row):
11            cleaned.append([cell.strip() for cell in row])
12    return header, cleaned
13
14def transform_data(header, data):
15    """Bước 3: Convert to list of dicts"""
16    return [dict(zip(header, row)) for row in data]
17
18def analyze(records):
19    """Bước 4: Tính thống kê"""
20    scores = [float(r["score"]) for r in records]
21    return {
22        "count": len(scores),
23        "mean": sum(scores) / len(scores),
24        "min": min(scores),
25        "max": max(scores),
26    }
27
28# Pipeline
29raw = """name,score,grade
30Alice,95,A
31Bob,87,B
32Charlie,92,A
33Diana,,B
34Eve,78,C"""
35
36data = load_data(raw)
37header, cleaned = clean_data(data)
38records = transform_data(header, cleaned)
39stats = analyze(records)
40
41print(f"Kết quả phân tích ({stats['count']} records):")
42print(f"  Mean: {stats['mean']:.1f}")
43print(f"  Min: {stats['min']:.0f} | Max: {stats['max']:.0f}")