title: pandas resample documentation
body: <p>So I completely understand how to use <a href="http://pandas-docs.github.io/pandas-docs-travis/generated/pandas.DataFrame.resample.html?highlight=dataframe%20resample#pandas.DataFrame.resample" rel="noreferrer">resample</a>, but the documentation does not do a good job explaining the options.</p>
  
  <p>So most options in the <code>resample</code> function are pretty straight forward except for these two:</p>
  
  <ul>
  <li>rule : the offset string or object representing target conversion</li>
  <li>how : string, method for down- or re-sampling, default to ‘mean’</li>
  </ul>
  
  <p>So from looking at as many examples as I found online I can see for rule you can do <code>'D'</code> for day, <code>'xMin'</code> for minutes, <code>'xL'</code> for milliseconds, but that is all I could find.</p>
  
  <p>for how I have seen the following: <code>'first'</code>, <code>np.max</code>, <code>'last'</code>, <code>'mean'</code>, and <code>'n1n2n3n4...nx'</code> where nx is the first letter of each column index.</p>
  
  <p>So is there somewhere in the documentation that I am missing that displays every option for <code>pandas.resample</code>'s rule and how inputs? If yes, where because I could not find it. If no, <strong>what are all the options for them?</strong></p>