tensorflow2 官网教程 面向初学者的快速入门

完整代码：

from __future__ import absolute_import, division, print_function, unicode_literals

import tensorflow as tf 


mnist = tf.keras.datasets.mnist
(x_train, y_train), (x_test, y_test) = mnist.load_data()
x_train, x_test = x_train/ 255.0, x_test / 255.0

model = tf.keras.models.Sequential([
    tf.keras.layers.Flatten(input_shape=(28, 28)),
    tf.keras.layers.Dense(128, activation = 'relu'),
    tf.keras.layers.Dropout(0.2),
    tf.keras.layers.Dense(10, activation= 'softmax')
])

model.compile(optimizer='adam',
            loss='sparse_categorical_crossentropy',
            metrics=['accuracy'])

model.fit(x_train, y_train, epochs=5)

model.evaluate(x_test, y_test, verbose=2)

码完就跑

Downloading data from https://storage.googleapis.com/tensorflow/tf-keras-datasets/mnist.npz
Traceback (most recent call last):
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/urllib/request.py", line 1317, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 1229, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 1275, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 1224, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 1016, in _send_output
    self.send(msg)
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 956, in send
    self.connect()
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/http/client.py", line 1392, in connect
    server_hostname=server_hostname)
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/ssl.py", line 412, in wrap_socket
    session=session
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/ssl.py", line 850, in _create
    self.do_handshake()
  File "/opt/anaconda3/envs/tensorflow2/lib/python3.7/ssl.py", line 1108, in do_handshake
    self._sslobj.do_handshake()
ConnectionResetError: [Errno 54] Connection reset by peer

数据集下不下来

离线下载 mnist.npz

百度网盘上有，直接下载下来，放到 .keras/datasets 目录下，再次运行。

mac 电脑上找了下这个目录， 在根目录下输入：

find ./ | grep datasets

看到有一条：

.//.keras/datasets

将下载好的 mnist.npz 放入这个目录后， 运行代码。