title: Python Data Frame resample on micro second
body: <p>I am working with resampling data frame and it works on hours, days mins, but doesn't resample less then sec. Program just hangs even on short time span. So am I missing something? </p>
  
  <p>I tried 0.000001S, U etc... Nothing worked so far.</p>
  
  <p>my time format:    2015-08-29 19:30:47.015506</p>
  
  <p>you can see varable sf represent resampling freq.</p>
  
  <pre><code>grph = df.set_index('Date and Time').resample(sf, len).astype(int)
  </code></pre>
  
  <p>How can I resample data frame on micro seconds granularity?</p>