choice_by_rate

import random
from typing import List
from pprint import pprint
from dataclasses import dataclass, field

debug = False


@dataclass
class Item:
    id: int = field(init=False)
    #     id: int
    rate: float


# FIXME: 总和不到1
def make_random_items(n: int) -> List[Item]:
    return [
        Item(id=i, exposure_rate=random.uniform(0.0, 1.0) * 0.5)
        for i in range(n)
    ]


# FIXME: 总和不到1
def make_random_sorted_items(n: int) -> List[Item]:
    items = make_items(n)
    items.sort(key=lambda d: d.rate, reverse=True)
    i = 0
    for d in items:
        d.id = i
        i += 1
    return items


def make_sorted_fixed_items() -> List[Item]:
    items = [
        Item(rate=0.5),
        Item(rate=0.3),
        Item(rate=0.1),
        Item(rate=0.1),
    ]
    i = 0
    for d in items:
        d.id = i
        i += 1

    return items


def show(d: List[Item]):
    from matplotlib import pyplot
    ids, rates = [], []
    for e in d:
        ids.append(e.id)
        rates.append(e.rate)
    pyplot.plot(ids, rates)
    pyplot.xlabel('rate')
    pyplot.ylabel('item id')
    pyplot.title('item_id & rate')
    pyplot.yticks([0.0, 0.25, 0.50, 0.75, 1.0])
    pyplot.xticks(ids)
    #     pyplot.fill_between(rates, ids, 10, color = 'green')
    pyplot.show()


def hit_proper_item_by_rate(d: List[Item]) -> Item:
    lucky_number = random.uniform(0.0, 1.0)
    cumulative_probability = 0.0
    if debug: print(f'\n> {lucky_number=}')
    for e in d:
        cumulative_probability += e.rate
        if cumulative_probability > lucky_number: break
    return e



def test(items: List[Item], amount: int = 100, tolerance: int = 10):
    print(f"概率测试 共{amount}次")
    kv: dict = {d.id: 0 for d in deliveries}
    for _ in range(amount):
        d = hit_proper_item_by_rate(items)
        kv[d.id] += 1
    for d in items:
        expect_amount = amount * d.rate
        hit_count = kv[d.id]
        result = abs(expect_amount - hit_count) < tolerance
        print(
            f"delivery-{d.id} 命中 {hit_count} 次, 符合预期吗(误差+-{tolerance})? {expect_amount} == {hit_count} => {result}"
        )


# items = make_random_items(5)
# items = make_random_sorted_items(3)
items = make_sorted_fixed_items()
pprint(items)
show(items)
d = hit_proper_item_by_rate(items)
print(f'命中: {d=}')

test(items, amount=300)
test(items, amount=3000)
test(items, amount=30000)
test(items, amount=300000)
test(items, amount=3000000)