网格搜索报错：(GridSearchCV): ‘ascii‘ codec can‘t encode characters in position 18-20: ordinal not in r

网格搜索报错：UnicodeEncodeError: ‘ascii’ codec can’t encode characters in position 18-20: ordinal not in range(128)

E:\DLstudy\Scripts\python.exe E:/PycharmProjects/DLstudy/run/train_model.py
[INFO] tuning hyperparameters...
Traceback (most recent call last):
  File "E:\PycharmProjects\DLstudy\run\train_model.py", line 22, in <module>
    model.fit(trainX, trainY)
  File "E:\DLstudy\lib\site-packages\sklearn\model_selection\_search.py", line 820, in fit
    with parallel:
  File "E:\DLstudy\lib\site-packages\joblib\parallel.py", line 725, in __enter__
    self._initialize_backend()
  File "E:\DLstudy\lib\site-packages\joblib\parallel.py", line 735, in _initialize_backend
    n_jobs = self._backend.configure(n_jobs=self.n_jobs, parallel=self,
  File "E:\DLstudy\lib\site-packages\joblib\_parallel_backends.py", line 494, in configure
    self._workers = get_memmapping_executor(
  File "E:\DLstudy\lib\site-packages\joblib\executor.py", line 20, in get_memmapping_executor
    return MemmappingExecutor.get_memmapping_executor(n_jobs, **kwargs)
  File "E:\DLstudy\lib\site-packages\joblib\executor.py", line 42, in get_memmapping_executor
    manager = TemporaryResourcesManager(temp_folder)
  File "E:\DLstudy\lib\site-packages\joblib\_memmapping_reducer.py", line 531, in __init__
    self.set_current_context(context_id)
  File "E:\DLstudy\lib\site-packages\joblib\_memmapping_reducer.py", line 535, in set_current_context
    self.register_new_context(context_id)
  File "E:\DLstudy\lib\site-packages\joblib\_memmapping_reducer.py", line 560, in register_new_context
    self.register_folder_finalizer(new_folder_path, context_id)
  File "E:\DLstudy\lib\site-packages\joblib\_memmapping_reducer.py", line 590, in register_folder_finalizer
    resource_tracker.register(pool_subfolder, "folder")
  File "E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py", line 191, in register
    self._send('REGISTER', name, rtype)
  File "E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py", line 204, in _send
    msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
UnicodeEncodeError: 'ascii' codec can't encode characters in position 18-20: ordinal not in range(128)

Process finished with exit code 1

解决方法

原报错代码：

model = GridSearchCV(LogisticRegression(), params, cv=3, n_jobs=-1)

将参数n_job=-1参数删去即可，改为：

model = GridSearchCV(LogisticRegression(), params, cv=3)

大概看了一下，这个参数是指示我们需要多少个处理器进行工作的

n_jobs : int, default=None
        Number of jobs to run in parallel.
        ``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
        ``-1`` means using all processors. See :term:`Glossary <n_jobs>`
        for more details.

如果指定n_jobs=-1的话，在底层有一步，使用ascii进行编码，但是每次都会编码失败。
所以如果我们不指定这个参数，则默认使用1个处理器进行工作。

如果确实想指定多个处理器

那么则需要修改我们的报错信息中出现问题的路径的代码了。
例如在我们报错信息中：

  File "E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py", line 204, in _send
    msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
UnicodeEncodeError: 'ascii' codec can't encode characters in position 18-20: ordinal not in range(128)

说明我出错的位置在E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py的204行 _send这个方法中，点进去
_send函数源代码：

  def _send(self, cmd, name, rtype):
        msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
        if len(name) > 512:
            # posix guarantees that writes to a pipe of less than PIPE_BUF
            # bytes are atomic, and that PIPE_BUF >= 512
            raise ValueError('name too long')
        nbytes = os.write(self._fd, msg)
        assert nbytes == len(msg)

将
msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
改为
msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('utf8')

也就是将编码方式改为utf-8，更改后代码如下：

```python
  def _send(self, cmd, name, rtype):
        msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('utf8')
        if len(name) > 512:
            # posix guarantees that writes to a pipe of less than PIPE_BUF
            # bytes are atomic, and that PIPE_BUF >= 512
            raise ValueError('name too long')
        nbytes = os.write(self._fd, msg)
        assert nbytes == len(msg)

然后再次运行代码。
别着急，还是会报错。因为我们只是修改了编码方式，还没有修改解码方式。
报错信息如下：

     .............(省略)
    splitted = line.strip().decode('ascii').split(':')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 18: ordinal not in range(128)
Traceback (most recent call last):
  File "E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py", line 253, in main
    splitted = line.strip().decode('ascii').split(':')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 18: ordinal not in range(128)

同样的，在报错信息中找到出错的路径：E:\DLstudy\lib\site-packages\joblib\externals\loky\backend\resource_tracker.py文件第253行出错了，我们找到相应的位置：

......(省略）
       with open(fd, 'rb') as f:
            while True:
                line = f.readline()
                if line == b'':  # EOF
                    break
                try:
                    splitted = line.strip().decode('ascii').split(':')
                    # name can potentially contain separator symbols (for
                    # instance folders on Windows)
                    cmd, name, rtype = (
                        splitted[0], ':'.join(splitted[1:-1]), splitted[-1])
......(省略）

我们只需要将
line.strip().decode('ascii').split(':')
替换为
line.strip().decode(''utf8).split(':')、
即可。

再次运行文件即可成功。