python要求用函数实现，文件

.编写程序：建立一个文件a.txt，a中每行包含以下数据：
30, 23, 45
32, 65, 47
33, 45, 67
生成文件B，B中每行是A中对应每行的数值平均值(保留两位小数点)。如以上数据，则b中的内容为：
32.67
48.00
48.33
要求用函数来实现。

from numpy import mean
f = open('C:/Users/clw31/Desktop/test.txt', encoding='gbk')

for line in f:
    a = line.strip().split(',')
    a = [int(x) for x in a]
    ave_a = mean(a)
    print(ave_a)

dirname=r'C:\Users\Administrator\Desktop'

def fun(): 
    with open(dirname + "/aaaa.txt", 'w+', encoding = 'utf-8') as f:
        f.write('30,23,45\n32,65,47\n33,45,67')
        f.seek(0)
        res = [sum(map(int, i.strip().split(","))) /3 for i in f.readlines()]
        res = [f'{i:.2f}\n' for i in res]
    with open(dirname + "/bbbb.txt", 'w', encoding = 'utf-8') as f1:
        f1.writelines(res)
        
fun()