"""
Урок 43. Summary session 11 — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/43-summary-session-11/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-43.py
"""



# ====================================================================
# Пример 1. Измерение времени
# ====================================================================
import time

start = time.time()
values = range(1_000_000)
elapsed_range = time.time() - start

start = time.time()
values_list = list(range(1_000_000))
elapsed_list = time.time() - start

print(f"range: создаётся мгновенно (лениво)")
print(f"list:  требует заполнить память, elapsed_list > 0: {elapsed_list > 0}")
# range: создаётся мгновенно (лениво)
# list:  требует заполнить память, elapsed_list > 0: True


# ====================================================================
# Пример 2. OrderedDict как очередь задач
# ====================================================================
from collections import OrderedDict

od = OrderedDict()
od["a"] = 1
od["b"] = 2
od["c"] = 3
print(od.popitem(last=False))  # первый вставленный элемент
print(od)
# ('a', 1)
# OrderedDict([('b', 2), ('c', 3)])

queue = OrderedDict([
    ("task1", "low"),
    ("task2", "high"),
    ("task3", "low"),
])

for key, value in list(queue.items()):
    if "high" in value:
        queue.move_to_end(key, last=False)
    elif "low" in value:
        queue.move_to_end(key)

print(queue)
# OrderedDict([('task2', 'high'), ('task1', 'low'), ('task3', 'low')])


# ====================================================================
# Пример 3. LRU-кэш на практике
# ====================================================================
from functools import lru_cache

@lru_cache(maxsize=128)
def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n - 1) + fibonacci(n - 2)

print(fibonacci(35))
print(fibonacci.cache_info())
# 9227465
# CacheInfo(hits=33, misses=36, maxsize=128, currsize=36)


# ====================================================================
# Пример 4. frozenset как ключ словаря
# ====================================================================
frozen = frozenset(["read", "write"])
permissions = {frozen: "editor"}
print(permissions[frozen])
# editor


# ====================================================================
# Пример 5. Counter: подсчёт частоты элементов
# ====================================================================
from collections import Counter

votes = ["red", "blue", "red", "green", "blue", "red"]
tally = Counter(votes)
print(tally)
print(tally.most_common(2))
# Counter({'red': 3, 'blue': 2, 'green': 1})
# [('red', 3), ('blue', 2)]


# ====================================================================
# Пример 6. deque: быстрое добавление и удаление с обоих концов
# ====================================================================
from collections import deque

recent_events = deque(maxlen=3)
for event in ["login", "click", "scroll", "logout"]:
    recent_events.append(event)
print(recent_events)
# deque(['click', 'scroll', 'logout'], maxlen=3)

history = deque([1, 2, 3])
history.appendleft(0)
history.append(4)
print(history)
# deque([0, 1, 2, 3, 4])


# ====================================================================
# Пример 7. defaultdict: группировка без ручной проверки ключа
# ====================================================================
from collections import defaultdict

words = ["apple", "banana", "avocado", "blueberry", "cherry"]
by_letter = defaultdict(list)
for word in words:
    by_letter[word[0]].append(word)
print(dict(by_letter))
# {'a': ['apple', 'avocado'], 'b': ['banana', 'blueberry'], 'c': ['cherry']}


# ====================================================================
# Пример 8. Основные операции со словарём
# ====================================================================
profile = {"name": "Alice", "age": 30}
profile["city"] = "Berlin"
profile.update({"age": 31, "email": "alice@example.com"})

if "email" in profile:
    print(profile["email"])

removed = profile.pop("email")
print(f"Удалено: {removed}")
print(profile)
# alice@example.com
# Удалено: alice@example.com
# {'name': 'Alice', 'age': 31, 'city': 'Berlin'}


# ====================================================================
# Пример 9. Передача функции в функцию
# ====================================================================
def double(x):
    return x * 2

def apply(func, data):
    return [func(x) for x in data]

print(apply(double, [1, 2, 3]))
# [2, 4, 6]


# ====================================================================
# Пример 10. Lambda с сортировкой
# ====================================================================
people = [("Mike", 19), ("Nancy", 35), ("Oscar", 33), ("Frank", 33)]

by_age = sorted(people, key=lambda p: p[1])
by_age_name = sorted(people, key=lambda p: (-p[1], p[0]))

print(by_age)
print(by_age_name)
# [('Mike', 19), ('Oscar', 33), ('Frank', 33), ('Nancy', 35)]
# [('Nancy', 35), ('Frank', 33), ('Oscar', 33), ('Mike', 19)]


# ====================================================================
# Пример 11. Парадигмы программирования: функциональный подход
# ====================================================================
# функциональный подход: новый список вместо изменения старого
numbers = [1, 2, 3]
doubled = [x * 2 for x in numbers]
print(doubled)
# [2, 4, 6]


# ====================================================================
# Пример 12. Ловушка: забытый list() и попытка изменить frozenset
# ====================================================================
numbers = [1, 2, 3]
doubled_iterator = map(lambda x: x * 2, numbers)
print(doubled_iterator)          # <map object at ...> — это не список
print(list(doubled_iterator))    # только так виден результат
# <map object at 0x...>
# [2, 4, 6]

frozen = frozenset([1, 2, 3])
try:
    frozen.add(4)
except AttributeError as error:
    print(f"Ошибка: {error}")
# Ошибка: 'frozenset' object has no attribute 'add'

try:
    wrong_key = {1, 2}
    lookup = {wrong_key: "value"}
except TypeError as error:
    print(f"Ошибка: {error}")
# Ошибка: unhashable type: 'set'