pyxis.py 文件源码

def get_sample(self, i):
        """Return the ith sample from `data_db`.

        Parameter
        ---------
        i : int
        """
        if 0 > i or self.nb_samples <= i:
            raise IndexError('The selected sample number is out of range: %d'
                             % i)

        # Convert the sample number to a string with trailing zeros
        key = encode_str('{:010}'.format(i))

        with self._lmdb_env.begin(db=self.data_db) as txn:
            # Read msgpack from LMDB and decode each value in it
            obj = msgpack.unpackb(txn.get(key))
            for k in obj:
                # Keys are stored as byte objects (hence the `decode_str`)
                obj[decode_str(k)] = msgpack.unpackb(
                    obj.pop(k), object_hook=decode_data)

        return obj