[英]Create a json tree from csv list in python
我正在嘗試從 python 中的一個簡單表構建一個 json 層次結構。
數據如下所示:
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
我正在尋找這樣的輸出:
{"$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":{}}}}}}}},
"$6":{"name":"test-name-6","children":"test-name-6"}}
我不知道會有多少“葉子”或“根”,或者來自 csv 的行的順序是什么。我的問題是,有沒有一種方法可以從子節點遞歸構建字典/列表取決於父母? 如何從python中樹的“葉子”部分生成分層樹?
謝謝您的幫助!
我也有一個基於 2 個循環的解決方案(1 個用於緩存,1 個用於構建),沒有 JSON 編碼器,它提供了您需要的輸出:
>>> import re
>>> from collections import defaultdict
>>> parents = defaultdict(list)
>>> for i, line in enumerate(file_.split('\n')):
if i != 0 and line.strip():
id_, parent, name = re.findall(r'[\d\w-]+', line)
parents[parent].append((id_, name))
>>> parents
defaultdict(<type 'list'>, {'10': [('1', 'test-name-1'), ('2', 'test-name-2'), ('5', 'test-name-5')], 'none': [('4', 'test-name-4'), ('6', 'test-name-6')], '1': [('7', 'test-name-7'), ('8', 'test-name-8')], '5': [('3', 'test-name-3')], '4': [('10', 'test-name-10')], '8': [('9', 'test-name-9')]})
好的,現在我們有了緩存,遞歸函數可以輕松構建我們想要的輸出:
>>> def build_tree(d, val):
return {'$' + id_: {'name': name, 'children': build_tree(d, id_)} for id_, name in d[val]}
我們只需要在之前構建的 dict 上調用它,值為'none'
,即樹根:
>>> from pprint import pprint
>>> pprint(build_tree(parents, 'none'))
{'$4': {'children': {'$10': {'children': {'$1': {'children': {'$7': {'children': {},
'name': 'test-name-7'},
'$8': {'children': {'$9': {'children': {},
'name': 'test-name-9'}},
'name': 'test-name-8'}},
'name': 'test-name-1'},
'$2': {'children': {},
'name': 'test-name-2'},
'$5': {'children': {'$3': {'children': {},
'name': 'test-name-3'}},
'name': 'test-name-5'}},
'name': 'test-name-10'}},
'name': 'test-name-4'},
'$6': {'children': {}, 'name': 'test-name-6'}}
>>>
要將所有子節點分配給其父節點,您可以對節點列表進行兩次傳遞。 第一遍將每個節點添加到UserDict
。 在第二遍中,每個節點的父節點都保證在UserDict
因此可以將節點添加到其父節點的children
節點中。
要序列化為 JSON,可以使用JSONEncoder
。
#!/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)
結果:
{"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": []}
給出的答案在 python 3.6 中對我不起作用,因為 Dict.Dict 已被棄用。 因此,我進行了一些更改以使其工作並通過讓用戶通過命令行指定 child_id、parent_id 和 child name 的列來對其進行一些概括。 請參見下文(我只是在學習,我確信這可以改進,但它適用於我的目的)。
""" Converts a CSV file with Parent/Child Hierarchy to a hierarchical JSON file for front-end processing (javascript/DS)
USAGE: csv2json.py <somefile.csv> a b c (column nrs of a=child_id, b=parent-id, c=name(of child))
ROOT of hierarchy should contain child_id and parent_id = 'none' or blank. name must exist """
import sys
import json
import csv
#import UserDict
from collections import UserDict
class Node(object):
def __init__(self, child_id, parent_id, name):
self.child_id = child_id
self.parent_id = parent_id
self.children = []
self.name = name
class NodeDict(UserDict):
def addNodes(self, nodes):
""" Add every node as a child to its parent_id by doing two passes."""
for i in (1, 2):
for node in nodes:
self.data[node.child_id] = node
if node.parent_id in self.data.keys():
if (node.parent_id != "none" or node.parent_id != "") and node not in self.data[node.parent_id].children:
self.data[node.parent_id].children.append(node)
class NodeJSONEncoder(json.JSONEncoder):
def default(self, node):
if type(node) == Node:
return {"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], 'r') as f:
reader = csv.reader(f)
for row in reader:
if not row[int(sys.argv[4])] : #skip if no name/label exists
continue
child_id, parent_id, name = row[int(sys.argv[2])] , row[int(sys.argv[3])] , row[int(sys.argv[4])]
nodes.append(Node(child_id, parent_id, name))
nodeDict = NodeDict()
nodeDict.addNodes(nodes)
rootNodes = [node for child_id, node in nodeDict.items()
if (node.parent_id == "none" or node.parent_id == "")]
for rootNode in rootNodes:
print(NodeJSONEncoder().encode(rootNode))
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