如何從csv構建嵌套的有序字典？

Question

我怎樣才能得到一個嵌套的字典，其中兩個鍵和子鍵正是以相同的順序為csv文件？

我試過了

import csv
from collections import OrderedDict

filename = "test.csv"
aDict = OrderedDict()

with open(filename, 'r') as f:
    csvReader = csv.DictReader(f)
    for row in csvReader:
        key = row.pop("key")
        aDict[key] = row

在哪里test.csv看起來像

key,number,letter
eins,1,a
zwei,2,b
drei,3,c

但是子詞典沒有排序（行字母和數字已更改）。 那么如何以有序的方式填充aDict[key] ？

Answer 1

您必須自己從csv.reader返回的行（序列）構建字典和子字典，而不是使用csv.DictReader 。

幸運的是，這很容易：

import csv
from collections import OrderedDict

filename = 'test.csv'
aDict = OrderedDict()

with open(filename, 'rb') as f:
    csvReader = csv.reader(f)
    fields = next(csvReader)
    for row in csvReader:
        temp = OrderedDict(zip(fields, row))
        key = temp.pop("key")
        aDict[key] = temp

import json  # just to create output
print(json.dumps(aDict, indent=4))

輸出：

{
    "eins": {
        "number": "1",
        "letter": "a"
    },
    "zwei": {
        "number": "2",
        "letter": "b"
    },
    "drei": {
        "number": "3",
        "letter": "c"
    }
}

Answer 2

這是一種方法：

import csv
from collections import OrderedDict

filename = "test.csv"
aDict = OrderedDict()

with open(filename, 'r') as f:
    order = next(csv.reader(f))[1:]
    f.seek(0)

    csvReader = csv.DictReader(f)
    for row in csvReader:
        key = row.pop("key")
        aDict[key] = OrderedDict((k, row[k]) for k in order)

Answer 3

csv.DictReader將行加載到常規dict而不是有序dict 。 您必須手動將csv讀取到OrderedDict才能獲得所需的訂單：

from collections import OrderedDict

filename = "test.csv"
dictRows = []

with open(filename, 'r') as f:
    rows = (line.strip().split(',') for line in f)
    # read column names from first row
    columns = rows.next()
    for row in rows:
        dictRows.append(OrderedDict(zip(columns, row)))

Answer 4

您可以利用現有的csv.DictReader類，但可以更改其返回的行。 為此，請將以下類添加到腳本的開頭：

class OrderedDictReader(csv.DictReader):
    def next(self):
        # Get a row using csv.DictReader
        row = csv.DictReader.next(self)

        # Create a new row using OrderedDict
        new_row = OrderedDict(((k, row[k]) for k in self.fieldnames))
        return new_row

然后，使用此類代替csv.DictReader ：

csvReader = OrderedDictReader(f)

您的其余代碼保持不變。