update.py

import pip
from subprocess import call
from pip._internal.utils.misc import get_installed_distributions

Source = ""

Sources = ["http://mirrors.aliyun.com/pypi/simple/","https://pypi.mirrors.ustc.edu.cn/simple/",\
"https://pypi.tuna.tsinghua.edu.cn/simple/"]

print("Please select a mirror, -1 to quit")

i = 0
for item in Sources:
    print(str(i) + " " + item)
    i += 1

i = input("Please input a value:")

i = int(i)

#index should between 0 and length

if i >= 0 and i < len(Sources):
    Source = " -i " + Sources[i]
elif i == -1:
    exit()

command = input(
    "Please input a command or do nothing * Follow with pip description:")

if command.strip() == '':
    for dist in get_installed_distributions():
        call(
            "pip install --upgrade " + dist.project_name + Source,
            shell=True)
else:
    call("pip install " + command +  Source, shell=True)