Question

我试图将一些JSON对象和两个整数传递给池。

for i in range(0, multiprocessing.cpu_count()-1):
    fromindex = i * chunklen
    toindex = (i+1) * chunklen
    chunkedData.append([data['features'][fromindex:toindex], weekdaytopredict, hourtopredict])
chunkedData.append([data['features'][toindex:], weekdaytopredict, hourtopredict])
parallelstart = time.time()
result = (pool.map(parallelUpdateWithDT, chunkedData))

data是包含一些多边形的geoJSON文件。我想分发这些多边形以进行并行处理。我将n/cpu_count()个多边形传递给parallelUpdateWithDT函数，该函数应该进一步处理它们。我的问题是类型错误：即使print(chunkedData)返回<class 'list'>，我也会发出以下错误：TypeError: a bytes-like object is required, not 'str'。我在哪里弄乱这个？完整堆栈跟踪：

---------------------------------------------------------------------------
RemoteTraceback                           Traceback (most recent call last)
RemoteTraceback: 
"""
Traceback (most recent call last):
  File "/usr/lib/python3.5/multiprocessing/pool.py", line 119, in worker
    result = (True, func(*args, **kwds))
  File "/usr/lib/python3.5/multiprocessing/pool.py", line 44, in mapstar
    return list(map(*args))
  File "<ipython-input-114-bf56cacb90b9>", line 34, in parallelUpdateWithDT
    if('rain' in result):
TypeError: a bytes-like object is required, not 'str'
"""

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

TypeError                                 Traceback (most recent call last)
<ipython-input-115-031a5e24ee66> in <module>()
----> 1 decisionTreePrediciton(3, 5)

<ipython-input-114-bf56cacb90b9> in decisionTreePrediciton(weekdaytopredict, hourtopredict)
     15     print (type(chunkedData))
     16 
---> 17     result = (pool.map(parallelUpdateWithDT, chunkedData))
     18     parallelend = time.time()
     19 

/usr/lib/python3.5/multiprocessing/pool.py in map(self, func, iterable, chunksize)
    258         in a list that is returned.
    259         '''
--> 260         return self._map_async(func, iterable, mapstar, chunksize).get()
    261 
    262     def starmap(self, func, iterable, chunksize=None):

/usr/lib/python3.5/multiprocessing/pool.py in get(self, timeout)
    606             return self._value
    607         else:
--> 608             raise self._value
    609 
    610     def _set(self, i, obj):

chunkedData的示例：

[[[{'geometry': {'coordinates': [[[10.914622377957983, 45.682007076150505], [10.927456267537572, 45.68179119797432], [10.927147329501077, 45.672795442796335], [10.914315493899755, 45.67301125363092], [10.914622377957983, 45.682007076150505]]], 'type': 'Polygon'}, ///////////////////////etc, waaay too big////////////, 'id': 6574, 'properties': {'cellId': 11454}}], 3, 5]

这是怎样的str？我不明白。谢谢你的帮助！

Answer 1

从您发布的代码中无法判断，但我怀疑您正在尝试检查str in是否为bytes。例如：

>>> bytes_obj = b'result'
>>> 'res' in bytes_obj
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: a bytes-like object is required, not 'str'

这意味着代码中的result类型为bytes。这里有两个决议。第一种是将'rain'转换为字节对象：

if b'rain' in result:
    ...

第二种方法是将result变为str：

result = result.decode(whatever_codec_it_should_be)

如果您要采用第二种方法，则应尽早将结果转换为str，以避免各种str与bytes头痛。通常，如果你不知道，你需要一个不同的编解码器，那么现在大多数事情都在utf-8之外，所以你可以尝试一下......

Python TypeError - 必需的字节对象而不是str

1 个答案: