TypeError:保存.npy文件时，write()参数必须为str，而不是字节 [英] TypeError: write() argument must be str, not bytes while saving .npy file

问题描述

我尝试在代码. keras.io/building-powerful-image-classification-models-using-very-little-data.html"rel =" noreferrer> keras博客文章.

I tried running the code in a keras blog post.

该代码将写入.npy文件，如下所示:

The code writes to a .npy file as follows:

bottleneck_features_train = model.predict_generator(generator, nb_train_samples // batch_size)
np.save(open('bottleneck_features_train.npy', 'w'),bottleneck_features_train)

然后从该文件读取:

def train_top_model():
    train_data = np.load(open('bottleneck_features_train.npy'))

现在我收到一条错误消息:

Now I get an error saying:

Found 2000 images belonging to 2 classes.
Traceback (most recent call last):
  File "kerasbottleneck.py", line 103, in <module>
    save_bottlebeck_features()
  File "kerasbottleneck.py", line 69, in save_bottlebeck_features
    np.save(open('bottleneck_features_train.npy', 'w'),bottleneck_features_train)
  File "/opt/anaconda3/lib/python3.6/site-packages/numpy/lib/npyio.py", line 511, in save
    pickle_kwargs=pickle_kwargs)
  File "/opt/anaconda3/lib/python3.6/site-packages/numpy/lib/format.py", line 565, in write_array
version)
  File "/opt/anaconda3/lib/python3.6/site-packages/numpy/lib/format.py", line 335, in _write_array_header
fp.write(header_prefix)
TypeError: write() argument must be str, not bytes

此后，我尝试将文件模式从"w"更改为"wb".导致在读取文件时出错:

After this, I tried changing the file mode from 'w' to 'wb'. This resulted in an error while reading the file:

Found 2000 images belonging to 2 classes.
Found 800 images belonging to 2 classes.
Traceback (most recent call last):
  File "kerasbottleneck.py", line 104, in <module>
    train_top_model()
  File "kerasbottleneck.py", line 82, in train_top_model
    train_data = np.load(open('bottleneck_features_train.npy'))
  File "/opt/anaconda3/lib/python3.6/site-packages/numpy/lib/npyio.py", line 404, in load
magic = fid.read(N)
  File "/opt/anaconda3/lib/python3.6/codecs.py", line 321, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x93 in position 0: invalid start byte

如何解决此错误?

推荐答案

博客文章中的代码针对Python 2，在Python 2中，使用字节串对文件进行读写.在Python 3中，您需要以二进制模式打开文件，以进行写入，然后再次读取:

The code in the blog post is aimed at Python 2, where writing to and reading from a file works with bytestrings. In Python 3, you need to open the file in binary mode, both for writing and then reading again:

np.save(
    open('bottleneck_features_train.npy', 'wb'),
    bottleneck_features_train)

阅读时:

train_data = np.load(open('bottleneck_features_train.npy', 'rb'))

请注意那里的模式参数中的b字符.

Note the b character in the mode arguments there.

我将使用该文件作为上下文管理器，以确保将其完全关闭:

I'd use the file as a context manager to ensure it is cleanly closed:

with open('bottleneck_features_train.npy', 'wb') as features_train_file
    np.save(features_train_file, bottleneck_features_train)

和

with open('bottleneck_features_train.npy', 'wb') as features_train_file:
    train_data = np.load(features_train_file)

无论如何，博客文章中的代码应同时使用这两项更改，因为在Python 2中，模式下没有b标志的文本文件具有特定于平台的换行符约定，并且Windows中，流中的某些字符将具有特定的含义(包括使文件显示得比出现EOF特征时实际显示的要短).使用二进制数据可能是一个真正的问题.

The code in the blog post should use both of these changes anyway, because in Python 2, without the b flag in the mode text files have platform-specific newline conventions translated, and on Windows certain characters in the stream will have specific meaning (including causing the file to appear shorter than it really is if a EOF characte appears). With binary data that could be a real problem.

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