p>使用 collections.defaultdict ：

  import csv 
 from collections import defaultdict 

 mydict = defaultdict（list）＃< --- 

 with open（'food.csv'，'r'）as csvfile：
 fileDialect = csv.Sniffer（）。sniff（csvfile .read（1024））
 csvfile.seek（0）
 dictReader = csv.DictReader（csvfile，dialect = fileDialect）
在dictReader中的行：
 mycategory = row.pop （Category）
 mydict [mycategory] ​​.append（row）＃将列出不存在的键

 mydict = dict（mydict）＃转换为普通字典可选）
 

I have a csv that looks like this:

Name;Category;Address
McFood;Fast Food;Street 1
BurgerEmperor;Fast Food;Way 1
BlueFrenchHorn;French;Street 12
PetesPizza;Italian;whatever
SubZero;Fast Food;Highway 6

and I want to make a dictionary with the category as keys and a list of dictionaries with the remaining data as values. So it shall look like this:

{'Fast Food' : [{'Name': 'McFood', 'Address': 'Street 1'}, 
                {'Name': 'BurgerEmperor', 'Address': 'Way 1'}],
                ...],
 'French' : [{'Name': 'BlueFrenchHorn', 'Address': 'Street12'}],
...}

(indentation here for better readability).

I tried it like the following snippet but I do not get anywhere from there:

import csv
mydict={}

with open ('food.csv', 'r') as csvfile:
        #sniff to find the format
        fileDialect = csv.Sniffer().sniff(csvfile.read(1024))
        csvfile.seek(0)
        #read the CSV file into a dictionary
        dictReader = csv.DictReader(csvfile, dialect=fileDialect)
        for row in dictReader:
            mycategory= row["Category"]
            del row("Category")
            mydict[mycategory]=row

Using collections.defaultdict:

import csv
from collections import defaultdict

mydict = defaultdict(list)  # <---

with open ('food.csv', 'r') as csvfile:
    fileDialect = csv.Sniffer().sniff(csvfile.read(1024))
    csvfile.seek(0)
    dictReader = csv.DictReader(csvfile, dialect=fileDialect)
    for row in dictReader:
        mycategory= row.pop("Category")
        mydict[mycategory].append(row)  # Will put a list for not-existing key

mydict = dict(mydict)  # Convert back to a normal dictionary (optional)