caffe的lmdb数据读取

import lmdb
import caffe
if __name__ == '__main__':
    lmdb_path=r'./DeepID2_train_lmdb'
#open lmdb
    lmdb_env = lmdb.open(lmdb_path)
    #begin transaction
    lmdb_txn = lmdb_env.begin()
    #get cursor
    lmdb_cursor = lmdb_txn.cursor()
    #get data object
    datum = caffe.proto.caffe_pb2.Datum()
    idx = 0
    min_val = 1000000
    max_val = -1
    label_dict = {}
    for key, value in lmdb_cursor:
        #parse back to datum
        datum.ParseFromString(value)
        #get y value
        label = datum.label
        label_dict[label] =1
        if int(label) > max_val:
          max_val = int(label)
        if int(label) < min_val:
          min_val = int(label)
        if label != 0:
          continue
        print('key = '+key+'  label = ' + str(label))
        idx += 1
        #if idx >30:
        #   break
    print('max_val:'+str(max_val))
    print('min_val:'+str(min_val))
    print(len(label_dict))
    for i in range(max_val):
        if i not in label_dict:
           print(i)
    lmdb_env.close()