将Python数组写入txt文件，每行一个数组

Question

我想将多个Python数组写入txt文件，每行一个数组。之后，我想逐行阅读Arrays。

我的正在进行的代码如下。我正在研究的问题涉及大约100,000个数组（L的长度）

from __future__ import division
from array import array

M = array('I',[1,2,3])
N = array('I',[10,20,30])

L = [M,N]

with open('manyArrays.txt','w') as file:
    for a in L:
        sA = a.tostring()
        file.write(sA + '\n')

with open('manyArrays.txt','r') as file:
    for line in file:   
        lineRead = array('I', [])
        lineRead.fromstring(line)
        print MRead

我收到的错误消息是

lineRead.fromstring(line)
ValueError: string length not a multiple of item size