Question

可能更容易解释一个例子。

想象一下我有这样的事情：

 word_dict = {"word": frequency}

示例我将通过段落循环，在该段落中我发现单词freq为

 word_dict = {"this":2,"that":4} # assume that all the cases have just these two words..

是的，这是一个奇怪的词典..

现在，每个段落都分配给一个故事，这个故事有一个id：

让我说得到这个：

{1234: {word_dict}} # where 1234 is the story id

然后这个故事连在一本书中：因此，如果执行类似book_dict[book_id][story_id]的操作，则会返回word_dict。

但很有可能同一本book_id，story_id会有不同的word_dict

我知道这听起来很奇怪..

所以我想要的是book_dict[book_id][story_id] = [{word_dict}]所以它会返回一个单词词典列表..

我该如何实现呢。

ERR。问题是否有意义？

Answer 1

book_dict = {}
for each book_id, story_id, word_dict in who_knows_what:
    if book_id not in book_dict:
        book_dict[book_id] = {}
    if story_id not in book_dict[book_id]:
        book_dict[book_id][story_id] = []
    book_dict[book_id][story_id].append( word_dict )

Answer 2

另一种选择是使用setdefault：

book_dict = {}
for each book_id, story_id, word_dict in who_knows_what:
    book_dict.setdefault(book_id, {}).setdefault(story_id, []).append(word_dict)

Answer 3

以下是Scott Hunter的答案缩短版本：

book_dict = {}
for book_id, story_id, word_dict in who_knows_what:
    book_dict[book_id] = book_dict.get(book_id, {})
    book_dict[book_id][story_id] = book_dict[book_id].get(story_id, [])
    book_dict[book_id][story_id].append( word_dict )

创建嵌套字典python

3 个答案: