python - 使用 csv.DictReader 创建嵌套字典

Question

我正在使用python csv module我有一个包含 3 列的 CSV:项目、零件、类别。

我想创建一个字典来组合所有类别，然后使用 Item:Part 对它们的值进行排序。

例如:

512 SSD SATA,42-000153,Hardware
5M DisplayPort 1.2 Cable,42-000135,Cable
90W AC Adapter,42-000146,Adapter
4 port USB hub,42-000126,Adapter

我得到的结果是:

mydict = {
    Hardware:{512 SSD SATA:42-000153},
    Cable:{5M DisplayPort 1.2 Cable,42-000135},
    Adapter:{90W AC Adapter:42-000146},
    Adapter:{4 port USB hub:42-000126}
    }

这几乎让我到达那里:

def build_dict(source_file):
    projects = defaultdict(dict)
    headers = ['Product', 'Part Number', 'Category']
    with open(source_file, 'rb') as fp:
        reader = csv.DictReader(fp, fieldnames=headers, dialect='excel',
                                skipinitialspace=True)
        for rowdict in reader:
            if None in rowdict:
                del rowdict[None]
            category = rowdict.pop("Category")
            projects[category] = rowdict
        return dict(projects)

source_file = 'test.csv'

我正在寻找的结果:

mydict = {
    Hardware:{512 SSD SATA:42-000153},
    Cable:{5M DisplayPort 1.2 Cable,42-000135},
    Adapter:{90W AC Adapter:42-000146,4 port USB hub:42-000126}
    }

请帮忙!

Answer 1

我会利用 Python 的内置函数来做到这一点:

import csv
from collections import defaultdict

mydict = defaultdict(dict)
with open('inventory.csv', 'rb') as inf:
    for row in csv.DictReader(inf, fieldnames=['Product', 'Part Number', 
                                               'Category']):
        mydict[row['Category']][row['Product']] = row['Part Number']

import json  # for pretty-printing result
print(json.dumps(mydict, indent=4))

输出:

{
    "Hardware": {
        "512 SSD SATA": "42-000153"
    },
    "Adapter": {
        "4 port USB hub": "42-000126",
        "90W AC Adapter": "42-000146"
    },
    "Cable": {
        "5M DisplayPort 1.2 Cable": "42-000135"
    }
}

FWIW，您也可以这样做，这需要多几行代码，但会使内循环中发生的事情更具可读性。结果是相同的。请注意，它使用 csv.reader 而不是 csv.DictReader。

import csv
from collections import defaultdict
from collections import namedtuple

Record = namedtuple('Record', ['product', 'part_number', 'category'])

mydict = defaultdict(dict)
with open('inventory.csv', 'rb') as inf:
    for rec in map(Record._make, csv.reader(inf)):
        mydict[rec.category][rec.product] = rec.part_number  # more readable