创建一个新字典来总结使用循环的原始字典。

Question

数据集或指定的字典是：

# A list of video reviews
# - Each review has the name of the video, the numer of views
#   and a list of user reviews.
# - Each user review has the user's name and the review they gave
#   to the video.

video_reviews = [
    {
        "name": "Cats doing nothing",
        "number_of_views": 450743,
        "reviews": [
            {"name": "Jeb", "review": 5},
            {"name": "Samantha", "review": 2},
            {"name": "Crystal", "review": 3},
        ]
    },
    {
        "name": "All Fail",
        "number_of_views": 1239734,
        "reviews": [
            {"name": "Crystal", "review": 5},
            {"name": "Frank", "review": 3},
            {"name": "Jeb", "review": 3},
        ]
    },
    {
        "name": "Runaway Nintendo",
        "number_of_views": 48343,
        "reviews": [
            {"name": "Samantha", "review": 4},
            {"name": "Bill", "review": 3},
            {"name": "Sarah", "review": 4},
        ]
    },
]

这是我的问题:我想定义一个函数并创建一个用户摘要--一个字典--其中键是用户的名字，值是他们已经查看过的视频列表。预期结果如下：

{
    "Jeb": ["Cats doing nothing", "All Fail"],
    "Samantha": ["Cats doing nothing","Runaway Nintendo"],
    "Crystal": ["Cats doing nothing", "All Fail"],
    "Frank": ["All Fail"],
    "Bill": ["Runaway Nintendo"],
    "Sarah": ["Runaway Nintendo"],
}

目前，我的代码是：

def create_user_summary(video_reviews):
    summary = {}
    for video in video_reviews:
        for person in video["reviews"]:
            user = person["name"]
            video_name = []
            if person["name"] == user:
                video_name.append(video["name"])
                summary[user] = video_name
    return summary

AssertionError: 
You returned:
    {'Jeb': ['All Fail'], 'Samantha': ['Runaway Nintendo'], 'Crystal': ['All Fail'], 'Frank': ['All Fail'], 'Bill': ['Runaway Nintendo'], 'Sarah': ['Runaway Nintendo']}
instead of:
    {'Jeb': ['Cats doing nothing', 'All Fail'], 'Samantha': ['Cats doing nothing', 'Runaway Nintendo'], 'Crystal': ['Cats doing nothing', 'All Fail'], 'Frank': ['All Fail'], 'Bill': ['Runaway Nintendo'], 'Sarah': ['Runaway Nintendo']}

如何修改代码并使输出与预期的输出匹配？

Answer 1

下面是您的代码的修改版本，我认为它提供了您想要的内容：

def create_user_summary(video_reviews):
    summary = {}
    for video in video_reviews:
        for person in video["reviews"]:
            summary.setdefault(person["name"], []).append(video["name"])
    return summary

结果“

{'Jeb': ['Cats doing nothing', 'All Fail'], 'Samantha': ['Cats doing nothing', 'Runaway Nintendo'], 'Crystal': ['Cats doing nothing', 'All Fail'], 'Frank': ['All Fail'], 'Bill': ['Runaway Nintendo'], 'Sarah': ['Runaway Nintendo']}

Answer 2

您可以为此使用一些内置的python函数，比如sorted和groupby，并将其与list和dict理解结合在一起：

from itertools import groupby
source = ((rev['name'], vid['name']) for vid in video_reviews for rev in vid['reviews'])
result = {k: list(m for _, m in g) for k, g in groupby(sorted(source), lambda x: x[0])}
print(result)

Answer 3

你可以用defaultdict，

from collections import defaultdict

result = defaultdict(list)
for item in video_reviews:
    for review in item['reviews']:
        result[review['name']].append(item['name'])
print(dict(result))

结果：

{'Jeb': ['Cats doing nothing', 'All Fail'],
 'Samantha': ['Cats doing nothing', 'Runaway Nintendo'],
 'Crystal': ['Cats doing nothing', 'All Fail'],
 'Frank': ['All Fail'],
 'Bill': ['Runaway Nintendo'],
 'Sarah': ['Runaway Nintendo']}