当您通过easy_install或pip安装时，它是否成功完成?全输出是多少?您正在使用哪个python安装?如果您正在将模块安装到系统目录(如果您正在使用系统python安装)，则可能需要在使用安装命令之前使用sudo。你的问题中没有太多有用的信息，但是一些工具可能会有帮助，包括:

echo $PYTHONPATH and/or echo $PATH: when importing modules, Python searches one of these environment variables (lists of directories, : delimited) for the module you want. Importing problems are often due to the right directory being absent from these lists which python, which pip, or which easy_install: these will tell you the location of each executable. It may help to know. Use virtualenv, like @JesseBriggs suggests. It works very well with pip to help you isolate and manage the modules and environment for separate Python projects.

也许有点跑题了，但我在导入PyYAML时遇到了问题。指出你需要导入yaml。(我猜是经典的rtfm…)

Python导入机制确实有效，所以:

你的PYTHONPATH是错误的， 您的库没有安装在您认为的位置 您有另一个具有相同名称的库来掩盖这个库

对我有用的是:

python -m pip install -user {package name}

该命令不需要sudo。这是在OSX Mojave上测试的。

I know, that this is very old post but I didn't find any answer that was useful in my case (I am using arch linux). I had a similar problem installing "nest_asyncio" package which was definitely installed (visible when listing all the installed packages). There is a right way for arch linux users of installing python packages (as it was already explained here by Emanuel Fontelles). In my case the solution was just to uninstall the remaining not-working package (in my case "nest_asyncio") and then installing it again using the following command:

sudo pacman - s python-"nest_asyncio .

这解决了所有的问题。

不确定这是否会帮助任何人，但我有一个类似的问题在Mac M1与zsh。原来我在我的.zshrc文件中设置了一个别名命令，与我的python命令(python3)同名。

为了解决这个问题，我只需要取消命令的别名。我跑:

unalias python3

从我的家庭终端和Visual Studio的终端。