"""Download the data from Yann's website, unless it's already here."""

if not os.path.exists(work_directory):

os.mkdir(work_directory)

filepath = os.path.join(work_directory, filename)

if not os.path.exists(filepath):

filepath, _ = urllib.urlretrieve(SOURCE_URL + filename, filepath)

statinfo = os.stat(filepath)

print('Succesfully downloaded', filename, statinfo.st_size, 'bytes.')

"""Extract the images into a 4D uint8 numpy array [index, y, x, depth]."""

print('Extracting', filename)

with gzip.open(filename) as bytestream:

magic = _read32(bytestream)

if magic != 2051:

raise ValueError(

'Invalid magic number %d in MNIST image file: %s' %

(magic, filename))

num_images = _read32(bytestream)

rows = _read32(bytestream)

cols = _read32(bytestream)

buf = bytestream.read(rows * cols * num_images)

data = numpy.frombuffer(buf, dtype=numpy.uint8)

data = data.reshape(num_images, rows, cols, 1)

"""Convert class labels from scalars to one-hot vectors."""

num_labels = labels_dense.shape[0]

index_offset = numpy.arange(num_labels) * num_classes

labels_one_hot = numpy.zeros((num_labels, num_classes))

labels_one_hot.flat[index_offset + labels_dense.ravel()] = 1

"""Extract the labels into a 1D uint8 numpy array [index]."""

print('Extracting', filename)

with gzip.open(filename) as bytestream:

magic = _read32(bytestream)

if magic != 2049:

raise ValueError(

'Invalid magic number %d in MNIST label file: %s' %

(magic, filename))

num_items = _read32(bytestream)

buf = bytestream.read(num_items)

labels = numpy.frombuffer(buf, dtype=numpy.uint8)

if one_hot:

return dense_to_one_hot(labels)

def __init__(self, images, labels, fake_data=False):

if fake_data:

self._num_examples = 10000

else:

assert images.shape[0] == labels.shape[0], (

"images.shape: %s labels.shape: %s" % (images.shape,

labels.shape))

self._num_examples = images.shape[0]

# Convert shape from [num examples, rows, columns, depth]

# to [num examples, rows*columns] (assuming depth == 1)

assert images.shape[3] == 1

images = images.reshape(images.shape[0],

images.shape[1] * images.shape[2])

# Convert from [0, 255] -> [0.0, 1.0].

images = images.astype(numpy.float32)

images = numpy.multiply(images, 1.0 / 255.0)

self._images = images

self._labels = labels

self._epochs_completed = 0

self._index_in_epoch = 0

@property

def images(self):

return self._images

@property

def labels(self):

return self._labels

@property

def num_examples(self):

return self._num_examples

@property

def epochs_completed(self):

return self._epochs_completed

def next_batch(self, batch_size, fake_data=False):

"""Return the next `batch_size` examples from this data set."""

if fake_data:

fake_image = [1.0 for _ in xrange(784)]

fake_label = 0

return [fake_image for _ in xrange(batch_size)], [

fake_label for _ in xrange(batch_size)]

start = self._index_in_epoch

self._index_in_epoch += batch_size

if self._index_in_epoch > self._num_examples:

# Finished epoch

self._epochs_completed += 1

# Shuffle the data

perm = numpy.arange(self._num_examples)

numpy.random.shuffle(perm)

self._images = self._images[perm]

self._labels = self._labels[perm]

# Start next epoch

start = 0

self._index_in_epoch = batch_size

assert batch_size <= self._num_examples

end = self._index_in_epoch

class DataSets(object):

pass

data_sets = DataSets()

if fake_data:

data_sets.train = DataSet([], [], fake_data=True)

data_sets.validation = DataSet([], [], fake_data=True)

data_sets.test = DataSet([], [], fake_data=True)

return data_sets

TRAIN_IMAGES = 'train-images-idx3-ubyte.gz'

TRAIN_LABELS = 'train-labels-idx1-ubyte.gz'

TEST_IMAGES = 't10k-images-idx3-ubyte.gz'

TEST_LABELS = 't10k-labels-idx1-ubyte.gz'

VALIDATION_SIZE = 5000

local_file = maybe_download(TRAIN_IMAGES, train_dir)

train_images = extract_images(local_file)

local_file = maybe_download(TRAIN_LABELS, train_dir)

train_labels = extract_labels(local_file, one_hot=one_hot)

local_file = maybe_download(TEST_IMAGES, train_dir)

test_images = extract_images(local_file)

local_file = maybe_download(TEST_LABELS, train_dir)

test_labels = extract_labels(local_file, one_hot=one_hot)

validation_images = train_images[:VALIDATION_SIZE]

validation_labels = train_labels[:VALIDATION_SIZE]

train_images = train_images[VALIDATION_SIZE:]

train_labels = train_labels[VALIDATION_SIZE:]

data_sets.train = DataSet(train_images, train_labels)

data_sets.validation = DataSet(validation_images, validation_labels)

data_sets.test = DataSet(test_images, test_labels)

return data_sets