Write numpy arrays to lmdb

Question

I\'m trying to write some numpy arrays in python to lmdb:

import numpy as np
import lmdb

def write_lmdb(filename):
    lmdb_env = lmdb.open(filename, map_size=i         


        

Answer 1

Wrap your transactions under with. And remember to convert the value from bytes (string) back to numpy array using np.fromstring.

To be honest, it is not a good idea to store numpy array in lmdb since conversion from array to bytes back to array will lose some informations (ex. shape). You can try storing a dict of numpy arrays using pickle.

def write_lmdb(filename):
    ...
    with lmdb_env.begin(write=True) as lmdb_txn:
        ...

def read_lmdb(filename):
    ...
    with lmdb_env.begin() as lmdb_txn:
        with lmdb_txn.cursor() as lmdb_cursor:
            ...
            print np.fromstring(value, dtype=np.float64)