如何在python中的json文件开头跳过文本

Question

我有一个json对象文件，在这个文件的开头是一个文本、日期、时间、IP地址的头。

我已经尝试过f.readlines()5:没有结果。我已经尝试了下一步(F)

我希望跳过5或6行文本，直接进入json数据。

下面是一个例子。

import jsonlines
import json

data_file = input("Enter a file to parse: ")
with jsonlines.open(data_file) as file:
    for obj in file:
        try:
            jsonparse = json.loads(obj)
        except Exception as e:
            pass
        print(obj)

错误：

jsonlines.jsonlines.InvalidLineError: line contains invalid json: Expecting value: line 1 column 1 (char 0) (line 1)

json文件顶部: Start: 07/02/2019 14:59:40.686

连接: 192.168.11.203

以下是完整的长错误：

Enter a file to parse: Play.raw
Traceback (most recent call last):
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\site-packages\jsonlines\jsonlines.py", line 159, in read
    value = self._loads(line)
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\json\__init__.py", line 348, in loads
    return _default_decoder.decode(s)
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\json\decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\json\decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:/Users/sdickey/PycharmProjects/Python Testing/Actall Data/testing.py", line 6, in <module>
    for obj in file:
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\site-packages\jsonlines\jsonlines.py", line 204, in iter
    skip_empty=skip_empty)
  File "C:\Users\sdickey\AppData\Local\Programs\Python\Python37\lib\site-packages\jsonlines\jsonlines.py", line 164, in read
    six.raise_from(exc, orig_exc)
  File "<string>", line 3, in raise_from
jsonlines.jsonlines.InvalidLineError: line contains invalid json: Expecting value: line 1 column 1 (char 0) (line 1)

Process finished with exit code 1

Answer 1

最好不要在内存中读取整个文件，而是一次读取一行文件。

假设输入文件包含：

first line
second line
third line
fourth line
fifth line
{ "k1": "val1", "k2": "val2" }
{ "k3": "val3", "k4": "val4" }

如果您只想跳过5行，您可以残忍地这样做：

import json

with open("test.txt") as f:
    for _ in range(5):
        next(f)
    for line in f:
        obj = json.loads(line)
        print(obj)

或使用枚举：

import json

with open("test.txt") as f:
    for i, line in enumerate(f):
        if i<5:
            continue
        obj = json.loads(line)
        print(obj)

或者使用itertools的下拉列表，同时：

import itertools as it
import json

with open("test.txt") as f:
    for i, line in it.dropwhile(lambda i: i[0]<5, enumerate(f)):
        obj = json.loads(line)
        print(obj)

Answer 2

我想你是想逐行转换成json。您需要通过\n将前5行添加到所有行中，然后加载它：

import json
with open("test.txt") as f:
  json_obj = "\n".join(f.readlines()[5:])
  jsonparse = json.loads(json_obj)
  print(jsonparse)