python 数组写入txt文档（数据之间用逗号分离）

import codecs
import numpy as np
text =np.zeros((3, 3))

str1 = u'新数据：rn'
f = codecs.open("text.txt",'w','utf-8')

f.write(str1)
for i in range(0,text.shape[0]):
    for j in range(text.shape[1]):
       f.write(str(text[i,j])+',')
    f.write('rn')
f.close()