代码示例
# -*- coding: utf-8 -*-

import numpy as np

matrix = np.arange(12).reshape(4, -1)
print(matrix)
"""
[[ 0  1  2]
 [ 3  4  5]
 [ 6  7  8]
 [ 9 10 11]]
"""

# 保存二维数组
np.savetxt("matrix.txt", matrix, fmt="%d", delimiter=",")

# 读取二维数组
m = np.loadtxt("matrix.txt", dtype=int, delimiter=",")
print(m)
"""
[[ 0  1  2]
 [ 3  4  5]
 [ 6  7  8]
 [ 9 10 11]]
"""

参考
python如何保存矩阵,保存matrix,保存numpy.ndarray