Python JSON编码器改为将NaN转换为'null'

问题描述

我正在编写代码以接收能够转换为JSON的任意对象(可能是嵌套的).

I'm writing code to receive an arbitrary object (possibly nested) capable of being converted to JSON.

Python内置JSON编码器的默认行为是将NaN转换为NaN，例如json.dumps(np.NaN)产生NaN.如何将此NaN值更改为'null'?

The default behavior for Python's builtin JSON encoder is to convert NaNs to NaN, e.g. json.dumps(np.NaN) results in NaN. How can I change this NaN value to 'null'?

我尝试子类JSONEncoder并覆盖了default()方法如下:

I tried to subclass JSONEncoder and override the default() method as follows:

from json import JSONEncoder, dumps
import numpy as np

class NanConverter(JSONEncoder):
    def default(self, obj):
        try:
            _ = iter(obj)
        except TypeError:
            if isinstance(obj, float) and np.isnan(obj):
                return "null"
        return JSONEncoder.default(self, obj)

>>> d = {'a': 1, 'b': 2, 'c': 3, 'e': np.nan, 'f': [1, np.nan, 3]}
>>> dumps(d, cls=NanConverter)
'{"a": 1, "c": 3, "b": 2, "e": NaN, "f": [1, NaN, 3]}'

预期结果:'{"a": 1, "c": 3, "b": 2, "e": null, "f": [1, null, 3]}'

推荐答案

这似乎实现了我的目标:

This seems to achieve my objective:

import simplejson


>>> simplejson.dumps(d, ignore_nan=True)
Out[3]: '{"a": 1, "c": 3, "b": 2, "e": null, "f": [1, null, 3]}'

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