為字典中的每個鍵查找字典中某些值的平均值

Question

我有一個字典，它有一個字符串 id 作為鍵，一個列表列表作為值。 列表列表的第一個元素是圖書類型，第二個元素是圖書評級。 它看起來像這樣：

{'id1': [['Horror', 4.0], ['Sci-Fi', 9.5], ['Horror', 9.0]],
'id2': [['Thriller', 2.3], ['Horror', 6.2], ['Thriller', 3.9]]}

我想要做的是平均出每個 id 的每個流派的評級。 所以最后，我想要一本這樣的字典：

{'id1': [['Horror', 6.5], ['Sci-Fi', 9.5]],
'id2': [['Thriller', 3.1], ['Horror', 6.2]]}

我一直在嘗試做的是：

#existing_dictionary is the dictionary above
dict = {}
 for bookAndRate in existing_dictionary.items(): 
      for bookGenrePlusRating in bookAndRate[1]: #bookAndRate prints out [['Comedy', 4.0], ['Comedy', 4.9], ['Adventure', 7.8]] 
            #bookGenrePlusRating prints out ['Comedy', 4.0], then on a separate line, ['Comedy', 4.9], then on a separate line ['Adventure', 7.8]
            if bookGenrePlusRating[0] in dict.values():
                dict[id[0]][1] += bookGenrePlusRating[1] 
            else:
                 dict[id[0]] = [bookGenrePlusRating[0], bookGenrePlusRating[1]]

但這只是給了我每個 id 中的最后一個元素。 所以我最終得到

{'id1': ['Horror', 9.0],
'id2': ['Thriller', 3.9]}

Answer 1

嘗試：

from statistics import mean

dct = {
    "id1": [["Horror", 4.0], ["Sci-Fi", 9.5], ["Horror", 9.0]],
    "id2": [["Thriller", 2.3], ["Horror", 6.2], ["Thriller", 3.9]],
}

out = {}
for k, v in dct.items():
    for genre, rating in v:
        out.setdefault(k, {}).setdefault(genre, []).append(rating)

out = {k: [[kk, mean(vv)] for kk, vv in v.items()] for k, v in out.items()}
print(out)

印刷：

{
    "id1": [["Horror", 6.5], ["Sci-Fi", 9.5]],
    "id2": [["Thriller", 3.0999999999999996], ["Horror", 6.2]],
}

---

如果你想舍入花車：

out = {
    k: [[kk, round(mean(vv), 2)] for kk, vv in v.items()]
    for k, v in out.items()
}
print(out)

印刷：

{
    "id1": [["Horror", 6.5], ["Sci-Fi", 9.5]],
    "id2": [["Thriller", 3.1], ["Horror", 6.2]],
}