title: How to plot two data sets with different time interval and have them share axis in Python Matplotlib
body: <p>I have two data sets, A and B:</p>
  
  <p>Set A: <br>
  <kbd>date time&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><kbd>data</kbd><br>
  <kbd>6/21/2016 00:00:01</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1</kbd><br>
  <kbd>6/21/2016 01:00:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2</kbd><br>
  <kbd>6/21/2016 02:03:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3</kbd><br></p>
  
  <p>Set B: <br>
  <kbd>date time&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><kbd>data</kbd><br>
  <kbd>6/21/2016 00:01:10</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;10</kbd><br>
  <kbd>6/21/2016 01:02:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;20</kbd><br>
  <kbd>6/21/2016 01:23:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;30</kbd><br>
  <kbd>6/21/2016 01:30:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;40</kbd><br>
  <kbd>6/21/2016 02:01:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;50</kbd><br></p>
  
  <p>I am able to plot two sets on two separate plots with roughly the same start and end time stamp.  (in actuality, Set B increment is 5 second, Set A increment is 1 minute)</p>
  
  <p>What I want to do is:<br>
  1) Fill both Set A and Set B with seconds (see below table). <br>
  2) Empty data is OK, it should be ignored by matplotter <br>
  3) Plot with new date-time <br>
  Purpose: I want to do this is to combine multiple data source (datetime-temperature, datetime-datalogger, etc) with single time line. </p>
  
  <p>My questions:<br>
  a) Is there a pre-built algorithm (matplotlib, datetime, some other modules) to accomplish 1)?<br>
  b) If a) is a negative, what is the best way to accomplish 1)?<br>
  c) Is there a better (easier) way to accomplish the purpose? </p>
  
  <p>Set A: <br>
  <kbd>date time&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><kbd>data</kbd><br>
  <kbd>6/21/2016 00:00:01</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1</kbd><br>
  <kbd>6/21/2016 00:00:02</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:00:03</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  ...<br>
  <kbd>6/21/2016 00:59:58</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:59:59</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 01:00:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2</kbd><br>
  <kbd>6/21/2016 01:00:01</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 01:00:02</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  ...<br>
  <kbd>6/21/2016 02:02:58</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 02:02:59</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 02:03:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3</kbd><br></p>
  
  <p>Set B: <br>
  <kbd>date time&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><kbd>data</kbd><br>
  <kbd>6/21/2016 00:00:01</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:00:02</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  ...<br>
  <kbd>6/21/2016 00:01:08</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:01:09</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:01:10</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;10</kbd><br>
  <kbd>6/21/2016 00:01:11</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 00:01:12</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  ...<br>
  <kbd>6/21/2016 02:00:58</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 02:00:59</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 02:01:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;50</kbd><br>
  ...<br>
  <kbd>6/21/2016 02:02:59</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br>
  <kbd>6/21/2016 02:03:00</kbd><kbd>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</kbd><br></p>