"""
Урок 31. Summary session 8 — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/31-summary-session-8/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-31.py
"""



# ====================================================================
# Пример 1. Ссылка на объект и id()
# ====================================================================
numbers = [1, 2, 3]
alias = numbers
alias.append(4)
print(numbers)                    # [1, 2, 3, 4]
print(alias)                      # [1, 2, 3, 4]
print(id(numbers) == id(alias))   # True


# ====================================================================
# Пример 2. Неизменяемые объекты ведут себя иначе
# ====================================================================
text1 = "hello"
text2 = text1
text2 += " world"
print(text1)                      # hello
print(text2)                      # hello world
print(id(text1) == id(text2))     # False


# ====================================================================
# Пример 3. Вложенные списки: чтение и изменение через несколько индексов
# ====================================================================
matrix = [[1, 2], [3, 4], [5, 6]]
print(matrix[1][0])   # 3

for row_index, row in enumerate(matrix):
    for col_index, value in enumerate(row):
        matrix[row_index][col_index] = value + 1
print(matrix)          # [[2, 3], [4, 5], [6, 7]]


# ====================================================================
# Пример 4. del: элемент, срез и имя
# ====================================================================
numbers = [10, 20, 30, 40, 50]
del numbers[1]
print(numbers)        # [10, 30, 40, 50]

del numbers[1:3]
print(numbers)        # [10, 50]

old_numbers = [1, 2, 3]
new_numbers = old_numbers
del old_numbers
print(new_numbers)    # [1, 2, 3] — объект жив, пока есть другая ссылка


# ====================================================================
# Пример 5. Поверхностная и глубокая копия
# ====================================================================
import copy

original = [[1, 2], [3, 4]]
shallow = original.copy()
deep = copy.deepcopy(original)

shallow[0][0] = 99
deep[1][0] = 0

print(original)   # [[99, 2], [3, 4]]
print(shallow)     # [[99, 2], [3, 4]]
print(deep)        # [[1, 2], [0, 4]]


# ====================================================================
# Пример 6. List comprehension: преобразование и фильтр
# ====================================================================
numbers = [1, 4, 6, 7, 9]
squares = [number ** 2 for number in numbers]
print(squares)   # [1, 16, 36, 49, 81]
print(numbers)   # [1, 4, 6, 7, 9] — исходный список не тронут

even_numbers = [number for number in range(10) if number % 2 == 0]
print(even_numbers)   # [0, 2, 4, 6, 8]


# ====================================================================
# Пример 7. Условное выражение if-else и вложенный обход
# ====================================================================
numbers = [2, 7, 5, 4, 1, 1, 7, 8]
modified = [number if number % 2 == 0 else -1 for number in numbers]
print(modified)   # [2, -1, -1, 4, -1, -1, -1, 8]

matrix = [[1, 2, 3], [4, 5, 6]]
flattened = [value for row in matrix for value in row]
print(flattened)   # [1, 2, 3, 4, 5, 6]


# ====================================================================
# Пример 8. zip(): параллельный обход и ограничение по короткой последовательности
# ====================================================================
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35, 40]
for name, age in zip(names, ages):
    print(f"{name} is {age} years old.")
# Alice is 25 years old.
# Bob is 30 years old.
# Charlie is 35 years old.

print(list(zip(names, ages)))
# [('Alice', 25), ('Bob', 30), ('Charlie', 35)]


# ====================================================================
# Пример 9. Стек и очередь: LIFO против FIFO
# ====================================================================
from collections import deque

stack = []
stack.append("open")
stack.append("edit")
stack.append("save")
print(stack.pop())   # save — последним пришёл, первым ушёл
print(stack)          # ['open', 'edit']

queue = deque(["print", "scan", "send"])
queue.append("archive")
print(queue.popleft())   # print — первым пришёл, первым ушёл
print(queue)               # deque(['scan', 'send', 'archive'])


# ====================================================================
# Пример 10. Устойчивая сортировка
# ====================================================================
words = ["orange", "mango", "apple", "banana", "kiwi", "cherry"]
for word in sorted(words, key=len):
    print(f"{len(word)}: {word}")
# 4: kiwi
# 5: mango
# 5: apple
# 6: orange
# 6: banana
# 6: cherry

data = [("b", 2), ("a", 1), ("a", 0)]
print(sorted(data, key=lambda pair: pair[0]))
# [('a', 1), ('a', 0), ('b', 2)]


# ====================================================================
# Пример 11. Практика: удаление хвоста после первого нуля
# ====================================================================
numbers = [1, 2, 0, 3, 4, 5]
if 0 in numbers:
    zero_index = numbers.index(0)
    del numbers[zero_index:]
print("Список после удаления:", numbers)
# Список после удаления: [1, 2]


# ====================================================================
# Пример 12. Практика: конвейер zip + comprehension
# ====================================================================
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
people = [f"{name} ({age})" for name, age in zip(names, ages)]
print(people)
# ['Alice (25)', 'Bob (30)', 'Charlie (35)']

list1 = [1, 2, 3]
list2 = [4, 5, 6]
products = [left * right for left in list1 for right in list2]
print(products)
# [4, 5, 6, 8, 10, 12, 12, 15, 18]


# ====================================================================
# Пример 12. Практика: конвейер zip + comprehension
# ====================================================================
from itertools import product
print([left * right for left, right in product(list1, list2)])
# [4, 5, 6, 8, 10, 12, 12, 15, 18] — тот же результат