raise IOError, 'Not a gzipped file'

There is an error:

File "tensorflow/models/image/mnist/convolutional.py", line 59, in extract_data
    bytestream.read(16)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gzip.py", line 268, in read
    self._read(readsize)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gzip.py", line 303, in _read
    self._read_gzip_header()
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gzip.py", line 197, in _read_gzip_header
    raise IOError, 'Not a gzipped file'

解决方法：

The code attempts to download the data files from the MNIST web site, and assumes it's properly downloaded if the file is present locally on your system. You might have a corrupted file, in which case deleting it and retrying might help. Otherwise, try to get the data via your browser directly from:

http://yann.lecun.com/exdb/mnist/train-images-idx3-ubyte.gz

http://yann.lecun.com/exdb/mnist/train-labels-idx1-ubyte.gz

http://yann.lecun.com/exdb/mnist/t10k-images-idx3-ubyte.gz

http://yann.lecun.com/exdb/mnist/t10k-labels-idx1-ubyte.gz