python脚本检查模块是否存在否则安装模块

Question

我有这个简单的 Python 脚本。我想在运行它之前包含某种条件来检查 Python 模块（在我下面的示例subprocess 中）。如果该模块不存在，请安装该模块，然后运行该脚本。如果该模块存在，请跳过该模块的安装并运行该脚本。我在网上看到的大多数类似情况都在苦苦挣扎。

import subprocess
ls_output = subprocess.check_output(['ls'])
print ls_output

Answer 1

您可以通过以下方式检查是否安装了 pycurl：

# if you want to now install pycurl and run it, it is much trickier 
# technically, you might want to check if pip is installed as well
import sys
import pip

def install(package):
    pip.main(['install', package])

try:
    import pycurl
except ImportError:
    print 'pycurl is not installed, installing it now!'
    install('pycurl')

# not recommended because http://stackoverflow.com/questions/7271082/how-to-reload-a-modules-function-in-python
import pycurl
. . . .
# better option:
print 'just installed pycurl, please rerun this script at your convenience'
sys.exit(1)