如何让Python函数基于start参数从指定章节计算剩余阅读页数？

我有一个存储书籍季、章节名称及对应页数的嵌套字典：

text = {
    1: {
        1: {"ch.name": "The Boy Who Lived", "pages": "146"},
        2: {"ch.name": "The Vanishing Glass", "pages": "126"},
    },
    2: {
        1: {"ch.name": "The Worst Birthday", "pages": "129"},
        2: {"ch.name": "Dobby's Warning", "pages": "125"},
    },
}

我编写了stranger_binger函数用于计算剩余可阅读页数并输出进度，但调用时传入start=(1,2)（从第1季第2章开始）、pages_left=300，结果没有从指定章节开始统计，而是从第1季第1章开始了。

原函数代码：

def stranger_binger(seasons,start,pages_left):
    num_pages_watched = 0

    for key1, value1 in seasons.items():
        for key2, value2 in value1.items():
            output = key1,key2,value2['ch.name'],value2['pages']
            output

    for key1, value1 in seasons.items():
        for key2, value2 in value1.items():
            pages_left = pages_left-int(value2['pages'])
            if start == start and pages_left > 0:
                pages_left
            if start == start and pages_left > 0:
                left = pages_left
                print(f"Watched Season {key1} Chapter {key2}: '{value2['ch.name']}', {pages_left} pages left !")
                num_pages_watched = num_pages_watched +1
            elif start == start and pages_left < 0:
                print(f"No more full Chapter today! Only {left} pages are left , but Season {key1} Chapter {key2}: '{value2['ch.name']}' has {value2['pages']}pages.")
                print(f"{num_pages_watched} chapter(s) watched today.")
                return start

stranger_binger({
    1: {
        1: {"ch.name": "The Boy Who Lived", "pages": "146"},
        2: {"ch.name": "The Vanishing Glass", "pages": "126"},
    },
    2: {
        1: {"ch.name": "The Worst Birthday", "pages": "129"},
        2: {"ch.name": "Dobby's Warning", "pages": "125"},
    },
},(1,2),300)

当前错误输出：

Watched Season 1 Chapter 1: 'The Boy Who Lived', 154 pages left !
Watched Season 1 Chapter 2: 'The Vanishing Glass', 28 pages left !
No more full Chapter today! Only 28 pages are left , but Season 2 Chapter 1: 'The Worst Birthday' has 129pages.
2 chapter(s) watched today.

预期输出：

Watched Season 1 Chapter 2: 'The Vanishing Glass', 174 pages left !
Watched Season 2 Chapter 1: 'The Worst Birthday', 45 pages left !
No more full Chapter today! Only 45 pages are left , but Season 2 Chapter 2: 'Dobby's Warning' has 125pages.
2 chapter(s) watched today.

def stranger_binger(seasons, start, pages_left):
    num_pages_watched = 0
    start_season, start_chapter = start
    started = False  # 标记是否到达开始章节

    # 按季的数字顺序遍历（兼容Python3.7以下无序字典的情况）
    for season_num in sorted(seasons.keys()):
        chapters = seasons[season_num]
        # 按章节数字顺序遍历
        for chapter_num in sorted(chapters.keys()):
            chapter_info = chapters[chapter_num]
            chapter_pages = int(chapter_info['pages'])
            
            # 未到达起始章节时跳过统计
            if not started:
                if season_num == start_season and chapter_num == start_chapter:
                    started = True
                else:
                    continue
            
            # 判断剩余页数是否足够阅读当前章节
            if pages_left >= chapter_pages:
                pages_left -= chapter_pages
                num_pages_watched += 1
                print(f"Watched Season {season_num} Chapter {chapter_num}: '{chapter_info['ch.name']}', {pages_left} pages left !")
            else:
                print(f"No more full Chapter today! Only {pages_left} pages are left , but Season {season_num} Chapter {chapter_num}: '{chapter_info['ch.name']}' has {chapter_pages} pages.")
                print(f"{num_pages_watched} chapter(s) watched today.")
                return start

stranger_binger({
    1: {
        1: {"ch.name": "The Boy Who Lived", "pages": "146"},
        2: {"ch.name": "The Vanishing Glass", "pages": "126"},
    },
    2: {
        1: {"ch.name": "The Worst Birthday", "pages": "129"},
        2: {"ch.name": "Dobby's Warning", "pages": "125"},
    },
}, (1,2), 300)

• 添加起始标记：新增started变量，用来判断是否到达指定的起始章节，未到达时跳过所有统计逻辑。
• 有序遍历章节：用sorted()处理季和章节的键，确保遍历顺序是数字从小到大，避免Python3.7以下版本字典无序导致的遍历顺序错误。
• 修正页数计算逻辑：原函数先直接扣减页数再判断剩余量，改为先判断剩余页数是否足够读当前章节，再执行扣减，逻辑更严谨。
• 移除无效代码：删除原函数中无意义的output变量赋值和空的if start == start判断语句。

内容的提问来源于stack exchange，提问作者Talkthattalk