从python中的csv列表创建一个json树 [英] Create a json tree from csv list in python

问题描述

我正在尝试从 python 中的一个简单表构建一个 json 层次结构.

I'm trying to build a json hierarchy from a simple table in python.

数据如下所示:

id         parent          name
1          10              test-name-1
2          10              test-name-2
3          5               test-name-3
4          none            test-name-4
5          10              test-name-5
6          none            test-name-6
7          1               test-name-7
8          1               test-name-8
9          8               test-name-9
10         4               test-name-10

我正在寻找这样的输出:

and I'm looking for an output like this:

{"$4":{"name":"test-name-4","children":{
      "$10":{"name":"test-name-10","children":{
            "$1":{"name":"test-name-1","children":{
                 "$7":{"name":"test-name-7","children":{}},
                 "$8":{"name":"test-name-8","children":{
                      "$9":{"name":"test-name-9","children":{}}}}}},
            "$2":{"name":"test-name-2","children":{}},
            "$5":{"name":"test-name-5","children":{
                 "$3":{"name":"test-name-3","children":{}}}}}}}},
 "$6":{"name":"test-name-6","children":"test-name-6"}}

我不知道会有多少叶子"或根"，或者来自 csv 的行的顺序是什么.我的问题是，有没有一种方法可以递归地构建字典/列表一个子节点到父节点?如何从python中树的叶子"部分生成分层树?

I have no idea how many "leaves" there will be or "roots", or what order the rows from the csv will come in. My question is, is there a way that I can recursively build a dictionary/list from a child node up to the parent? How can I produce a hierarchical tree from the "leaf" pieces of the tree in python?

感谢您的帮助！

推荐答案

要将所有子节点分配给其父节点，您可以对节点列表进行两次遍历.第一遍将每个节点添加到 UserDict.在第二遍中，每个节点的父节点都保证在 UserDict 中，因此可以将节点添加到其父节点的 children.

To assign all child nodes to its parent, you can do two passes over the list of nodes. The first pass adds each node to a UserDict. In the second pass the parent of each node is guaranteed to be in the UserDict so the node can be added to the children of its parent.

要序列化为 JSON，JSONEncoder 可以使用.

To serialize to JSON a JSONEncoder can be used.

#!/usr/bin/env python

import sys
import json
import UserDict

class Node(object):
    def __init__(self, nid, parent, name):
        self.nid = nid
        self.parent = parent
        self.children = []
        self.name = name

class NodeDict(UserDict.UserDict):
    def addNodes(self, nodes):
        """ Add every node as a child to its parent by doing two passes."""
        for i in (1, 2):
            for node in nodes:
                self.data[node.nid] = node
                if node.parent in self.data.keys():
                    if node.parent != "none" and
                       node not in self.data[node.parent].children:
                        self.data[node.parent].children.append(node)

class NodeJSONEncoder(json.JSONEncoder):
    def default(self, node):
        if type(node) == Node:
            return {"nid":node.nid, "name":node.name, "children":node.children}
        raise TypeError("{} is not an instance of Node".format(node))

if __name__ == "__main__":
    nodes = []

    with open(sys.argv[1]) as f:
        for row in f.readlines()[1:]:
            nid, parent, name = row.split()
            nodes.append(Node(nid, parent, name))

    nodeDict = NodeDict()
    nodeDict.addNodes(nodes)

    rootNodes = [node for nid, node in nodeDict.items()
                 if node.parent == "none"]
    for rootNode in rootNodes:
        print NodeJSONEncoder().encode(rootNode)

结果:

{"name": "test-name-4", "nid": "4", "children":[
     {"name": "test-name-10", "nid": "10", "children":[
         {"name": "test-name-1", "nid": "1", "children":[
            {"name": "test-name-7", "nid": "7", "children": []},
            {"name": "test-name-8", "nid": "8", "children":[
                {"name": "test-name-9", "nid": "9", "children": []}]}]},
         {"name": "test-name-2", "nid": "2", "children": []},
         {"name": "test-name-5", "nid": "5", "children":[
             {"name": "test-name-3", "nid": "3", "children": []}]}]}]}
{"name": "test-name-6", "nid": "6", "children": []}

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