在python 3中使用pip导入运行时安装的模块 [英] Import runtime installed module using pip in python 3

问题描述

我想在运行时安装和导入Python 3模块.

I want to install and import Python 3 modules at runtime.

我正在使用以下功能在运行时使用pip安装模块:

I'm using the following function to install modules at runtime using pip:

def installModules(modules):
    for module in modules:
        print("Installing module {}...".format(module))

        subprocess.call([sys.executable, "-m", "pip", "install", "--user", module])

该模块已成功安装，但是安装完成后，我无法在运行时导入它.所以，如果我这样做:

The module is installed successfully, but I'm not able to import it at runtime, after the installation finishes. So if I do:

modules = [ "wget", "zipfile2" ]
installModules(module)
import wget

我得到一个ModuleNotFoundError.在那之后，如果我开始另一个Python 3会话，则可以使用模块，例如wget，表示已经安装了模块，但不适用于当前的Python 3会话.

I get a ModuleNotFoundError. If, after that, I start another Python 3 session, I am able to use the modules e.g. wget, which means that the modules have been installed, but they are not available for this current Python 3 session.

在Python 3中是否可以在同一Python 3会话中即在安装后立即安装并导入已安装的模块?

Is it possible in Python 3 to install and then import the installed modules in the same Python 3 session i.e. right after installation?

谢谢！

在sudo apt-get install python3-pip之后，在VirtualBox内的全新Ubuntu 19.04上安装，运行以下脚本:

On a fresh Ubuntu 19.04 install inside VirtualBox, after a sudo apt-get install python3-pip, running the following script:

import os, sys
import subprocess


def installModules(modules):
    for module in modules:
        print("Installing module {}...".format(module))

        subprocess.call([sys.executable, "-m", "pip", "install", "--user", module])

def process():
    modulesToInstall = [ "wget", "zipfile2" ]
    installModules(modulesToInstall)

process()

import wget

def main():
    wget.download("http://192.168.2.234/test/configure.py")

if __name__ == "__main__":
    main()

我得到:

user@user-VirtualBox:~$ python3 script.py
Installing module wget...
Collecting wget
Installing collected packages: wget
Successfully installed wget-3.2
Installing module zipfile2...
Collecting zipfile2
  Using cached https://files.pythonhosted.org/packages/60/ad/d6bc08f235b66c11bbb76df41b973ce93544a907cc0e23c726ea374eee79/zipfile2-0.0.12-py2.py3-none-any.whl
Installing collected packages: zipfile2
Successfully installed zipfile2-0.0.12
Traceback (most recent call last):
  File "script.py", line 17, in <module>
    import wget
ModuleNotFoundError: No module named 'wget'

Python 3版本是:

The Python 3 version is:

user@user-VirtualBox:~$ python3 --version
Python 3.7.3

pip3版本为:

user@user-VirtualBox:~$ pip3 --version
pip 18.1 from /usr/lib/python3/dist-packages/pip (python 3.7)

其他信息:

user@user-VirtualBox:~$ whereis python3
python3: /usr/bin/python3.7m /usr/bin/python3.7-config /usr/bin/python3.7 /usr/bin/python3 /usr/bin/python3.7m-config /usr/lib/python3.7 /usr/lib/python3.8 /usr/lib/python3 /etc/python3.7 /etc/python3 /usr/local/lib/python3.7 /usr/include/python3.7m /usr/include/python3.7 /usr/share/python3 /usr/share/man/man1/python3.1.gz

有什么想法吗?

推荐答案

默认情况下，启动时 Python 添加用户站点包 dir (在模块搜索路径中，我将其称为 USPD ).但这仅在目录存在于文件系统(磁盘)上时发生.我没有找到任何官方文档来支持此声明 ¹ ，因此我花了一些时间进行调试，并想知道为什么事情看起来如此怪异

By default, at startup Python adds the user site-packages dir (I'm going to refer to it as USPD) in the module search paths. But this only happens if the directory exists on the file system (disk). I didn't find any official documentation to support this statement ¹, so I spent some time debugging and wondering why things seem to be so weird.

以上行为对此特定方案(pip install --user)具有重大影响.考虑将要安装模块的 Python 进程的状态(启动时):

The above behavior has a major impact on this particular scenario (pip install --user). Considering the state (at startup) of the Python process that will install modules:

1. USPD 存在:

• 事情很简单，一切正常确定

USPD 不存在:

• 模块安装将创建它
• 但是，由于它不在模块搜索路径中，因此那里安装的所有模块将无法用于(简单的) import 语句

启动另一个 Python 进程时，它将属于 #1.

When another Python process is started, it will fall under #1.

要解决问题，应将 USPD 手动添加到模块搜索路径. (开头)脚本如下所示:

To fix things, USPD should be manually added to module search paths. Here's how the (beginning of the) script should look like:

import sys
import os
import subprocess
import site

user_site = site.getusersitepackages()
if user_site not in sys.path:
    sys.path.append(user_site)

# ...

@ EDIT0 :

@EDIT0:

¹ 我刚遇到

¹ I just came across [Python]: PEP 370 -- Per user site-packages directory - Implementation (emphasis is mine):

站点模块获取一个新方法 adduserpackage()，该方法将适当的目录添加到搜索路径中. 如果在启动Python时该目录不存在，则不会添加该目录.

The site module gets a new method adduserpackage() which adds the appropriate directory to the search path. The directory is not added if it doesn't exist when Python is started.

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