[英]How to extract values from nested JSON array using pandas
我有一個很大的JSON文件(400k行)。 我正在嘗試隔離以下內容:
政策-“說明”
策略項目-“用戶”和“數據庫值”
JSON文件-https: //pastebin.com/hv8mLfgx
熊貓的預期產量: https : //imgur.com/a/FVcNGsZ
在整個“文件”中,“策略項”之后的所有內容都會重復重復。 我已經嘗試了下面的代碼來隔離“用戶”。 它似乎不起作用,我正在嘗試將所有這些都轉儲為CSV。
Edit *這是我嘗試嘗試的解決方案,但無法使其正常工作- 對pandas dataframe的深度嵌套JSON響應
from pandas.io.json import json_normalize as Jnormal
import json
import pprint, csv
import re
with open("Ranger_Policies_20190204_195010.json") as file:
jsonDF = json.load(file)
for item in jsonDF['policies'][0]['policyItems'][0]:
print ('{} - {} - {}'.format(jsonDF['users']))
編輯2:我有一些可以抓住一些用戶的工作代碼,但並不能抓住所有這些用戶。 25中只有11。
from pandas.io.json import json_normalize as Jnormal
import json
import pprint, csv
import re
with open("Ranger_Policies_20190204_195010.json") as file:
jsonDF = json.load(file)
pNode = Jnormal(jsonDF['policies'][0]['policyItems'], record_path='users')
print(pNode.head(500))
編輯3:這是最終的工作副本,但是我仍然沒有復制我所有的TABLE數據。 我設置了一個循環以簡單地忽略一切。 捕獲所有內容,然后在Excel中對其進行排序,是否有人對我無法捕獲所有TABLE值有任何想法?
json_data = json.load(file)
with open("test.csv", 'w', newline='') as fd:
wr = csv.writer(fd)
wr.writerow(('Database name', 'Users', 'Description', 'Table'))
for policy in json_data['policies']:
desc = policy['description']
db_values = policy['resources']['database']['values']
db_tables = policy['resources']['table']['values']
for item in policy['policyItems']:
users = item['users']
for dbT in db_tables:
for user in users:
for db in db_values:
_ = wr.writerow((db, user, desc, dbT))```
在這里,Pandas太過強大了:csv標准模塊就足夠了。 您只需迭代策略以提取描述和數據庫值,接下來訪問policyItems以提取用戶:
with open("Ranger_Policies_20190204_195010.json") as file:
jsonDF = json.load(file)
with open("outputfile.csv", newline='') as fd:
wr = csv.writer(fd)
_ = wr.writerow(('Database name', 'Users', 'Description'))
for policy in js['policies']:
desc = policy['description']
db_values = policy['resources']['database']['values']
for item in policy['policyItems']:
users = item['users']
for user in users:
for db in db_values:
if db != '*':
_ = wr.writerow((db, user, desc))
這是一種實現方法,假設您的json
數據位於名為json_data
的變量中
from itertools import product
def make_dfs(data):
cols = ['db_name', 'user', 'description']
for item in data.get('policies'):
description = item.get('description')
users = item.get('policyItems', [{}])[0].get('users', [None])
db_name = item.get('resources', {}).get('database', {}).get('values', [None])
db_name = [name for name in db_name if name != '*']
prods = product(db_name, users, [description])
yield pd.DataFrame.from_records(prods, columns=cols)
df = pd.concat(make_dfs(json_data), ignore_index=True)
print(df)
db_name user description
0 m2_db hive Policy for all - database, table, column
1 m2_db rangerlookup Policy for all - database, table, column
2 m2_db ambari-qa Policy for all - database, table, column
3 m2_db af34 Policy for all - database, table, column
4 m2_db g748 Policy for all - database, table, column
5 m2_db hdfs Policy for all - database, table, column
6 m2_db dh10 Policy for all - database, table, column
7 m2_db gs22 Policy for all - database, table, column
8 m2_db dh27 Policy for all - database, table, column
9 m2_db ct52 Policy for all - database, table, column
10 m2_db livy_pyspark Policy for all - database, table, column
在Python 3.5.1
和pandas==0.23.4
上測試
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