Write mnist image to lmdb with python

write_mnist_data_to_lmdb.py

from mnist import MNIST
import numpy as np
import cv2
import lmdb
import caffe
mndata = MNIST('./data')
images, labels = mndata.load_training()
labels = np.array(labels)
images = np.array(images).reshape(len(labels), 28, 28).astype(np.uint8)

print type(images[0][0][0])

count = 0
env = lmdb.open('mnist_lmdb', map_size=1000*1000*1000)

txn = env.begin(write=True)
for i in xrange(len(labels)):
    print i
    datum = caffe.proto.caffe_pb2.Datum()
    datum.channels = 1
    datum.height = 28
    datum.width = 28
    datum.data = images[i].tobytes()
    datum.label = labels[i]
    str_id = '{:08}'.format(i)
    txn.put(str_id, datum.SerializeToString())

    count = count + 1

    if count % 1000 == 0:
        txn.commit()
        txn = env.begin(write=True)

if count % 1000 != 0:
    txn.commit()
env.close()