问题:为什么Python无法解析此JSON数据?

我在文件中有此JSON:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": [
        "id": "valore"
    ],
    "om_points": "value",
    "parameters": [
        "id": "valore"
    ]
}

我编写了以下脚本来打印所有JSON数据:

import json
from pprint import pprint

with open('data.json') as f:
    data = json.load(f)

pprint(data)

但是,该程序会引发异常:

Traceback (most recent call last):
  File "<pyshell#1>", line 5, in <module>
    data = json.load(f)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting ',' delimiter: line 13 column 13 (char 213)

如何解析JSON并提取其值?

I have this JSON in a file:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": [
        "id": "valore"
    ],
    "om_points": "value",
    "parameters": [
        "id": "valore"
    ]
}

I wrote this script to print all of the JSON data:

import json
from pprint import pprint

with open('data.json') as f:
    data = json.load(f)

pprint(data)

This program raises an exception, though:

Traceback (most recent call last):
  File "<pyshell#1>", line 5, in <module>
    data = json.load(f)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting ',' delimiter: line 13 column 13 (char 213)

How can I parse the JSON and extract its values?


回答 0

您的数据不是有效的JSON格式。您有[]什么时候应该拥有{}

  • []用于JSON数组,list在Python 中称为
  • {}用于JSON对象(dict在Python 中称为JSON对象)

JSON文件的外观如下:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": {
        "id": "valore"
    },
    "om_points": "value",
    "parameters": {
        "id": "valore"
    }
}

然后,您可以使用您的代码:

import json
from pprint import pprint

with open('data.json') as f:
    data = json.load(f)

pprint(data)

使用数据,您现在还可以找到类似的值:

data["maps"][0]["id"]
data["masks"]["id"]
data["om_points"]

试试看,看看是否有意义。

Your data is not valid JSON format. You have [] when you should have {}:

  • [] are for JSON arrays, which are called list in Python
  • {} are for JSON objects, which are called dict in Python

Here’s how your JSON file should look:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": {
        "id": "valore"
    },
    "om_points": "value",
    "parameters": {
        "id": "valore"
    }
}

Then you can use your code:

import json
from pprint import pprint

with open('data.json') as f:
    data = json.load(f)

pprint(data)

With data, you can now also find values like so:

data["maps"][0]["id"]
data["masks"]["id"]
data["om_points"]

Try those out and see if it starts to make sense.


回答 1

data.json应该看起来像这样:

{
 "maps":[
         {"id":"blabla","iscategorical":"0"},
         {"id":"blabla","iscategorical":"0"}
        ],
"masks":
         {"id":"valore"},
"om_points":"value",
"parameters":
         {"id":"valore"}
}

您的代码应为:

import json
from pprint import pprint

with open('data.json') as data_file:    
    data = json.load(data_file)
pprint(data)

请注意,这仅在Python 2.6及更高版本中有效,因为它取决于。在Python 2.5中使用from __future__ import with_statement,在Python <= 2.4中,请参见Justin Peel的答案,该答案基于该答案。

您现在还可以像这样访问单个值:

data["maps"][0]["id"]  # will return 'blabla'
data["masks"]["id"]    # will return 'valore'
data["om_points"]      # will return 'value'

Your data.json should look like this:

{
 "maps":[
         {"id":"blabla","iscategorical":"0"},
         {"id":"blabla","iscategorical":"0"}
        ],
"masks":
         {"id":"valore"},
"om_points":"value",
"parameters":
         {"id":"valore"}
}

Your code should be:

import json
from pprint import pprint

with open('data.json') as data_file:    
    data = json.load(data_file)
pprint(data)

Note that this only works in Python 2.6 and up, as it depends upon the . In Python 2.5 use from __future__ import with_statement, in Python <= 2.4, see Justin Peel’s answer, which this answer is based upon.

You can now also access single values like this:

data["maps"][0]["id"]  # will return 'blabla'
data["masks"]["id"]    # will return 'valore'
data["om_points"]      # will return 'value'

回答 2

贾斯汀·皮尔(Justin Peel)的回答确实很有帮助,但是,如果您使用的是Python 3,则应按以下方式读取JSON:

with open('data.json', encoding='utf-8') as data_file:
    data = json.loads(data_file.read())

注意:使用json.loads代替json.load。在Python 3中,json.loads采用字符串参数。json.load采用类似文件的对象参数。data_file.read()返回一个字符串对象。

老实说,在大多数情况下,将所有json数据加载到内存中都不是问题。

Justin Peel’s answer is really helpful, but if you are using Python 3 reading JSON should be done like this:

with open('data.json', encoding='utf-8') as data_file:
    data = json.loads(data_file.read())

Note: use json.loads instead of json.load. In Python 3, json.loads takes a string parameter. json.load takes a file-like object parameter. data_file.read() returns a string object.

To be honest, I don’t think it’s a problem to load all json data into memory most cases.


回答 3

data = []
with codecs.open('d:\output.txt','rU','utf-8') as f:
    for line in f:
       data.append(json.loads(line))
data = []
with codecs.open('d:\output.txt','rU','utf-8') as f:
    for line in f:
       data.append(json.loads(line))

回答 4

“超JSON”或简称“ ujson”可以处理[]您的JSON文件输入中的内容。如果您正在将程序中的JSON输入文件作为JSON元素列表读取;例如,[{[{}]}, {}, [], etc...]ujson可以处理字典列表的任何任意顺序,即列表字典。

您可以在Python包索引中找到ujson,并且该API与Python的内置json库几乎相同。

如果您要加载较大的JSON文件,则ujson也会更快。与提供的相同链接中的其他Python JSON库相比,您可以看到性能详细信息。

“Ultra JSON” or simply “ujson” can handle having [] in your JSON file input. If you’re reading a JSON input file into your program as a list of JSON elements; such as, [{[{}]}, {}, [], etc...] ujson can handle any arbitrary order of lists of dictionaries, dictionaries of lists.

You can find ujson in the Python package index and the API is almost identical to Python’s built-in json library.

ujson is also much faster if you’re loading larger JSON files. You can see the performance details in comparison to other Python JSON libraries in the same link provided.


回答 5

如果您使用的是Python3,则可以尝试将(connection.json文件)JSON 更改为:

{
  "connection1": {
    "DSN": "con1",
    "UID": "abc",
    "PWD": "1234",
    "connection_string_python":"test1"
  }
  ,
  "connection2": {
    "DSN": "con2",
    "UID": "def",
    "PWD": "1234"
  }
}

然后使用以下代码:

connection_file = open('connection.json', 'r')
conn_string = json.load(connection_file)
conn_string['connection1']['connection_string_python'])
connection_file.close()
>>> test1

If you’re using Python3, you can try changing your (connection.json file) JSON to:

{
  "connection1": {
    "DSN": "con1",
    "UID": "abc",
    "PWD": "1234",
    "connection_string_python":"test1"
  }
  ,
  "connection2": {
    "DSN": "con2",
    "UID": "def",
    "PWD": "1234"
  }
}

Then using the following code:

connection_file = open('connection.json', 'r')
conn_string = json.load(connection_file)
conn_string['connection1']['connection_string_python'])
connection_file.close()
>>> test1

回答 6

在这里,您可以使用修改后的data.json文件:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": [{
        "id": "valore"
    }],
    "om_points": "value",
    "parameters": [{
        "id": "valore"
    }]
}

您可以使用以下几行在控制台上调用或打印数据:

import json
from pprint import pprint
with open('data.json') as data_file:
    data_item = json.load(data_file)
pprint(data_item)

预期输出print(data_item['parameters'][0]['id'])

{'maps': [{'id': 'blabla', 'iscategorical': '0'},
          {'id': 'blabla', 'iscategorical': '0'}],
 'masks': [{'id': 'valore'}],
 'om_points': 'value',
 'parameters': [{'id': 'valore'}]}

预期输出print(data_item['parameters'][0]['id'])

valore

Here you go with modified data.json file:

{
    "maps": [
        {
            "id": "blabla",
            "iscategorical": "0"
        },
        {
            "id": "blabla",
            "iscategorical": "0"
        }
    ],
    "masks": [{
        "id": "valore"
    }],
    "om_points": "value",
    "parameters": [{
        "id": "valore"
    }]
}

You can call or print data on console by using below lines:

import json
from pprint import pprint
with open('data.json') as data_file:
    data_item = json.load(data_file)
pprint(data_item)

Expected output for print(data_item['parameters'][0]['id']):

{'maps': [{'id': 'blabla', 'iscategorical': '0'},
          {'id': 'blabla', 'iscategorical': '0'}],
 'masks': [{'id': 'valore'}],
 'om_points': 'value',
 'parameters': [{'id': 'valore'}]}

Expected output for print(data_item['parameters'][0]['id']):

valore

回答 7

该解析有两种类型。

  1. 从系统路径解析文件中的数据
  2. 从远程URL解析JSON。

从文件中,您可以使用以下内容

import json
json = json.loads(open('/path/to/file.json').read())
value = json['key']
print json['value']

该小节解释了使用两种情况的完整解析和获取值。使用Python解析JSON

There are two types in this parsing.

  1. Parsing data from a file from a system path
  2. Parsing JSON from remote URL.

From a file, you can use the following

import json
json = json.loads(open('/path/to/file.json').read())
value = json['key']
print json['value']

This arcticle explains the full parsing and getting values using two scenarios.Parsing JSON using Python


回答 8

作为python3用户

loadloads方法之间的区别非常重要,尤其是当您从文件中读取json数据时。

如文档中所述:

json.load:

使用此转换表将fp(支持.read()的文本文件或包含JSON文档的二进制文件)反序列化为Python对象。

json.loads:

json.loads:使用此转换表将s(包含JSON文档的str,字节或字节数组实例)反序列化为Python对象。

json.load方法可以读取二进制文件,因此可以直接读取打开的json文档。

with open('./recipes.json') as data:
  all_recipes = json.load(data)

结果,您的json数据以根据此转换表指定的格式可用:

https://docs.python.org/3.7/library/json.html#json-to-py-table

As a python3 user,

The difference between load and loads methods is important especially when you read json data from file.

As stated in the docs:

json.load:

Deserialize fp (a .read()-supporting text file or binary file containing a JSON document) to a Python object using this conversion table.

json.loads:

json.loads: Deserialize s (a str, bytes or bytearray instance containing a JSON document) to a Python object using this conversion table.

json.load method can directly read opened json document since it is able to read binary file.

with open('./recipes.json') as data:
  all_recipes = json.load(data)

As a result, your json data available as in a format specified according to this conversion table:

https://docs.python.org/3.7/library/json.html#json-to-py-table


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