尝试通过 TF 下载 cifar-10 并获取证书错误

Question

我开始研究机器视觉，并尝试通过 python 代码直接下载 CIFAR-10，但一直被证书错误阻止。

不是 python 专家，不知道如何解决这个问题：

我执行python代码：

import numpy as np
import matplotlib.pyplot as plt
from tensorflow.keras.layers import Input, Conv2D, Dense, Flatten, Dropout
from tensorflow.keras.layers import GlobalMaxPooling2D, MaxPooling2D
from tensorflow.keras.layers import BatchNormalization
from tensorflow.keras.models import Model
cifar10 = tf.keras.datasets.cifar10

然后如果失败并出现此错误：

Downloading data from https://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz
Traceback (most recent call last):
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 1317, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 1252, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 1298, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 1247, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 1026, in _send_output
    self.send(msg)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 966, in send
    self.connect()
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\http\client.py", line 1422, in connect
    server_hostname=server_hostname)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\ssl.py", line 423, in wrap_socket
    session=session
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\ssl.py", line 870, in _create
    self.do_handshake()
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\ssl.py", line 1139, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1076)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\site-packages\keras\utils\data_utils.py", line 274, in get_file
    urlretrieve(origin, fpath, dl_progress)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\site-packages\keras\utils\data_utils.py", line 82, in urlretrieve
    response = urlopen(url, data)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 222, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 525, in open
    response = self._open(req, data)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 543, in _open
    '_open', req)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 503, in _call_chain
    result = func(*args)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 1360, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "C:\Users\test1\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 1319, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1076)>

我不确定如何手动下载数据集并让 python 从磁盘加载，或者强制它忽略错误。

任何帮助将不胜感激。提前致谢。

Answer 1

出现错误是因为您没有安装正确的证书，并且 https 查询无法连接到 cifar-10 数据库。

您可以绕过 python 并从以下位置手动下载它：cifar-10-python.tar.gz。然后，您只需将 python 指向您下载文件的任何位置。

或者，如果您使用的是 Mac，那么您可以尝试通过运行以下文件来安装所需的证书：/Applications/Python\ 3.6/Install\ Certificates.command，然后再次运行您的脚本

或者， 编辑此文件的本地副本cifar-10.py 并重新运行您的脚本。

# line 78
origin = 'https://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz'

# and change it to be:
origin = 'http://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz'

根据您安装 tensorflow 的方式，该文件可能存在于几个位置。