查找设施数量最多的城市

Question

我目前正在尝试破解一个编程难题，该难题具有非常简单的数据框host，其中有两列名为city 和amenities（均为object 数据类型）。现在，两列中的条目可以重复多次。以下是host 的前几个条目在下方

City    Amenities                                            Price($)
NYC    {TV,"Wireless Internet", "Air conditioning","Smoke      8
        detector",Essentials,"Lock on bedroom door"} 
LA     {"Wireless Internet",Kitchen,Washer,Dryer,"First aid    
        kit",Essentials,"Hair dryer","translation missing: 
         en.hosting_amenity_49","translation missing: 
         en.hosting_amenity_50"} 
                                                               10
SF     {TV,"Cable TV",Internet,"Wireless Internet",Kitchen,"Free 
        parking on premises","Pets live on this 
        property",Dog(s),"Indoor fireplace","Buzzer/wireless 
        intercom",Heating,Washer,Dryer,"Smoke detector","Carbon 
        monoxide detector","First aid kit","Safety card","Fire e 
        extinguisher",Essentials,Shampoo,"24-hour check- 
        in",Hangers,"Hair dryer",Iron,"Laptop friendly 
        workspace","translation missing: 
        en.hosting_amenity_49","translation missing: 
        en.hosting_amenity_50","Self Check-In",Lockbox}        15
NYC    {"Wireless Internet","Air 
        conditioning",Kitchen,Heating,"Suitable for events","Smoke 
        detector","Carbon monoxide detector","First aid kit","Fire 
        extinguisher",Essentials,Shampoo,"Lock on bedroom 
        door",Hangers,"translation missing: 
        en.hosting_amenity_49","translation missing: 
        en.hosting_amenity_50"}                                20
LA     {TV,Internet,"Wireless Internet","Air 
        conditioning",Kitchen,"Free parking on 
        premises",Essentials,Shampoo,"translation missing: 
        en.hosting_amenity_49","translation missing: 
        en.hosting_amenity_50"}
LA    {TV,"Cable TV",Internet,"Wireless Internet",Pool,Kitchen,"Free 
       parking on premises",Gym,Breakfast,"Hot tub","Indoor 
       fireplace",Heating,"Family/kid friendly",Washer,Dryer,"Smoke 
       detector","Carbon monoxide detector",Essentials,Shampoo,"Lock 
       on bedroom door",Hangers,"Private entrance"}           28

.....

问题。输出设施数量最多的城市。

我的尝试。我尝试使用groupby() 函数根据city 使用host.groupby('city'). 列对其进行分组现在，我需要计数成功的数量每套便利设施中的元素。由于数据类型不同，len() 函数不起作用，因为集合中的每个元素之间都有\（例如，如果我使用host['amenities'][0],，则输出为"{TV,\"Wireless Internet\",\"Air conditioning\",\"Smoke detector\",\"Carbon monoxide detector\",Essentials,\"Lock on bedroom door\",Hangers,Iron}"。将len() 应用于此输出会导致 134，这显然是不正确的）。我尝试使用 host['amenities'][0].strip('\n') 删除 \, 但 len() 函数仍然给出 134.

谁能帮我解决这个问题？

我的解决方案，灵感来自 ddejohn 的解决方案：

### Transform each "string-type" entry in column "amenities" to "list" type
host["amenities"] = host["amenities"].str.replace('["{}]', "", regex=True).str.split(",")

## Create a new column that count all the amenities for each row 
entry host["am_count"] = [len(data) for data in host["amenities"]]

## Output the index in the new column resulting from aggregation over the column `am_count` grouped by `city` 
host.groupby("city")["am_count"].agg("sum").argmax()

Answer 1

解决方案

import functools

# Process the Amenities strings into sets of strings
host["amenities"] = host["amenities"].str.replace('["{}]', "", regex=True).str.split(",").apply(set)

# Groupby city, perform the set union to remove duplicates, and get count of unique amenities
amenities_by_city = host.groupby("city")["amenities"].apply(lambda x: len(functools.reduce(set.union, x))).reset_index()

输出：

  city  amenities
0   LA         27
1  NYC         17
2   SF         29

让城市拥有最多的便利设施是通过

实现的

city_with_most_amenities = amenities_by_city.query("amenities == amenities.max()")

输出：

  city  amenities
2   SF         29