title: Error in install rpy2 on windows 10
body: <p>I got this error when using <code>pip to install rpy2</code> on my computer:</p>
  
  <pre><code>C:\Python27\Scripts&gt;pip install rpy2
  Collecting rpy2
    Using cached rpy2-2.8.2.tar.gz
      Complete output from command python setup.py egg_info:
      Warning: Tried to guess R's HOME but no command (R) in the PATH.
  
      ----------------------------------------
  Command "python setup.py egg_info" failed with error code 1 in c:\users\isaac\appdata\local\temp\pip-build-_n5cg0\rpy2\
  </code></pre>
  
  <p>I think this is just an error with the <code>R</code> directory on my computer.  How do I indicate the correct directory on <code>pip</code>?</p>