python 3 : nested dictionary with multiple keys from csv

Question

数据看起来像这样:

id,outer,inner1,inner2,inner3
123,"Smith,John",a,b,c
123,"Smith,John",d,e,f
123,"Smith,John",g,h,i
456,"Williams,Tim",xx,yy,zz
456,"Williams,Tim",vv,ww,uu
456,"Miller,Ray",rrr,sss,ttt
456,"Miller,Ray",qqq,www,ppp

我希望生成的字典是

{'123': {'Smith,John': 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'},
 '456': {'Williams,Tim': 'xx', 'yy', 'zz', 'vv', 'ww', 'zz'},
        {'Miller,Ray': 'rrr', 'sss', 'ttt', 'qqq', 'www', 'ppp'}}

我尝试改编 Python Creating A Nested Dictionary From CSV File 接受的答案，但此方法会在每一行覆盖字典，因此只有每个 id 的最后一行最终出现在字典中。

Answer 1

collections.defaultdict 使用每行的第一个元素作为外部字典键，然后使用第二个元素作为内部字典键，并将行中的其余值添加到列表中作为内部字典键的值:

import csv
from collections import defaultdict
with open("in.txt" ) as f:
    next(f) # skip header
    d = defaultdict(lambda: defaultdict(list))
    r = csv.reader(f)
    for row in r:
        d[row[0]][row[1]].extend(row[2:])

from pprint import pprint as pp

pp(dict(d))

输出:

{'123': {'Smith,John': ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']},
 '456': {'Miller,Ray': ['rrr', 'sss', 'ttt', 'qqq', 'www', 'ppp'],
         'Williams,Tim': ['xx', 'yy', 'zz', 'vv', 'ww', 'uu']}}

由于您使用的是 python3，我们可以使用 * 在循环中解压缩以使代码更好一些:

with open("in.txt") as f:
    next(f)  # skip header
    d = defaultdict(lambda: defaultdict(list))
    r = csv.reader(f)
    for k1, k2, *vals in r:
        d[k1][k2].extend(vals))