pandas 读取json在MultiIndex上不起作用 [英] pandas read json not working on MultiIndex

问题描述

我正在尝试通过pd.read_json读取通过df.to_json()创建的数据帧，但是却得到了ValueError.我认为这可能与索引是MultiIndex的事实有关，但是我不确定如何处理.

I'm trying to read in a dataframe created via df.to_json() via pd.read_json but I'm getting a ValueError. I think it may have to do with the fact that the index is a MultiIndex but I'm not sure how to deal with that.

55k行的原始数据帧称为psi，我通过以下方式创建了test.json:

The original dataframe of 55k rows is called psi and I created test.json via:

psi.head().to_json('test.json')

此处是print psi.head().to_string()的输出，如果您想用那个.

Hereis the output of print psi.head().to_string() if you want to use that.

当我对这小部分数据(5行)进行处理时，我得到一个ValueError.

When I do it on this small set of data (5 rows), I get a ValueError.

! wget --no-check-certificate https://gist.githubusercontent.com/olgabot/9897953/raw/c270d8cf1b736676783cc1372b4f8106810a14c5/test.json
import pandas as pd
pd.read_json('test.json')

这是完整的堆栈:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-14-1de2f0e65268> in <module>()
      1 get_ipython().system(u' wget https://gist.githubusercontent.com/olgabot/9897953/raw/c270d8cf1b736676783cc1372b4f8106810a14c5/test.json'>)
      2 import pandas as pd
----> 3 pd.read_json('test.json')

/home/obot/virtualenvs/envy/lib/python2.7/site-packages/pandas/io/json.pyc in read_json(path_or_buf, orient, typ, dtype, convert_axes, convert_dates, keep_default_dates, numpy, precise_float, date_unit)
    196         obj = FrameParser(json, orient, dtype, convert_axes, convert_dates,
    197                           keep_default_dates, numpy, precise_float,
--> 198                           date_unit).parse()
    199 
    200     if typ == 'series' or obj is None:

/home/obot/virtualenvs/envy/lib/python2.7/site-packages/pandas/io/json.pyc in parse(self)
    264 
    265         else:
--> 266             self._parse_no_numpy()
    267 
    268         if self.obj is None:

/home/obot/virtualenvs/envy/lib/python2.7/site-packages/pandas/io/json.pyc in _parse_no_numpy(self)
    481         if orient == "columns":
    482             self.obj = DataFrame(
--> 483                 loads(json, precise_float=self.precise_float), dtype=None)
    484         elif orient == "split":
    485             decoded = dict((str(k), v)

ValueError: No ':' found when decoding object value

> /home/obot/virtualenvs/envy/lib/python2.7/site-packages/pandas/io/json.py(483)_parse_no_numpy()
    482             self.obj = DataFrame(
--> 483                 loads(json, precise_float=self.precise_float), dtype=None)
    484         elif orient == "split":

但是当我在整个数据帧(55k行)上执行此操作时，我得到一个无效的指针错误，IPython内核死亡.有什么想法吗?

But when I do it on the whole dataframe (55k rows) then I get an invalid pointer error and the IPython kernel dies. Any ideas?

首先添加了json的生成方式.

added how the json was generated in the first place.

推荐答案

这未实现ATM，请在此处查看问题: https://github.com/pydata/pandas/issues/4889 .

This is not implemented ATM, see the issue here: https://github.com/pydata/pandas/issues/4889.

您可以简单地首先重置索引，例如

You can simply reset the index first, e.g

df.reset_index().to_json(...)

它将起作用.

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