title: How to reinstall an installed python package in an virtual env?
body: <p>I have installed some python packages in an virtual environment (venv1) that I have created before (using pip, which automatically downloaded the packages and its dependencies), now I need to create another virtual environment (venv2) with a subset of packages installed in venv1. But how can I do without using internet? I figure out some ideas but I not sure if they are possible:</p>
  
  <ul>
  <li>By copying the venv1 to venv2 and uninstall unwanted packages</li>
  <li>By copying directories of the packages in site-package from the venv1 to venv2</li>
  <li>By extract one by one packages files from venv1 then create the file setup.py, fill it according and install in venv2 (hope not, because it will be tedious and can introduce errors)</li>
  <li>Maybe there is a way to generate eggs from installed packages or extract it with any tool? How?</li>
  </ul>
  
  <p>So what is the better way to do this?</p>
  
  <p>Thanks</p>