title: Efficiently getting older versions of R packages
body: <p>A recurring question on SO is that package xx is not available for R version 2.xx.xx. For <a href="https://stackoverflow.com/questions/16091096/can-not-install-package-in-r">example</a> the <code>gplots</code> package requires the user to have R 3.0 installed in order for it to install. You can get older versions in the Archive of CRAN, but:</p>
  
  <ul>
  <li>It is not easy to see which version of the package you need to get for a specific R version.</li>
  <li>You need to build the package from source, which is primarily a (mild) challenge under Windows.</li>
  </ul>
  
  <p>My question is the following: is there a more effective workflow in getting older package versions which match your older version of R? In the spirit of having different package repositories for different version of ubuntu. </p>
  
  <p>I know one option would be to just get the latest version of R, but there might be some pressing reason to stick to a certain version of R. For example, one could be interested in repeating an old experiment which relies on an old version of R and support packages. Or one is limited by the system administration.</p>