以chile/name格式将Csv转换为json

我尝试使用Python将CSV中的数据转换为JSON,格式如下: https://gist.github.com/mbostock/1093025 这样我可以修改一些 http://d3js.org/ 示例。

我找到了一些关于如何进行类似转换的帖子,但与嵌套的{'name':name,'children'=[]}格式完全不同。

我尝试了以下代码,但这给了我错误

以下是我的csv

L1  L2                L3        SIZE
CB  CB Current Acct Tween/Youth 10
CB  CB Current Acct Students    20

以下是编写的代码:

import json
import csv

class Node(object):
    def __init__(self, name, size=None):
        self.name = name
        self.children = []
        self.size = size

    def child(self, cname, size=None):
        child_found = [c for c in self.children if c.name == cname]
        if not child_found:
            _child = Node(cname, size)
            self.children.append(_child)
        else:
            _child = child_found[0]
        return _child

    def as_dict(self):
        res = {'name': self.name}
        if self.size is None:
            res['children'] = [c.as_dict() for c in self.children]
        else:
            res['size'] = self.size
        return res


root = Node('Segments')

with open('C:\\Desktop\\Book1.csv', 'r') as f:
    reader = csv.reader(f)
    p = next(reader)
    for row in p:
        grp1, grp2, grp3, size = row
        root.child(grp1).child(grp2).child(grp3, size)


print(json.dumps(root.as_dict(), indent=4))

但我得到如下错误:

Traceback (most recent call last):
File "C:/Desktop/untitled/converting.py", line 34, in <module>
grp1, grp2, grp3, size = row
ValueError: not enough values to unpack (expected 4, got 2)

预期输出为

{
 "name": "Community",
 "children": [
  {
   "name": "CB",
   "children": [
    {
     "name": " CB Current Acct",
     "children": [
      {"name": "Tween/Youth", "size": 10},
      {"name": "Students", "size": 20}
     ]
}
]
}
]
}