title: google charts with two curves not aligned with the time
body: <p>I want to display 2 curves. To show temperatures in 2 rooms. 
  X-axis is the time.
  The time is at the level of the minute.
  so I see the chart for one day.
  THe temeprature is logged when it changes only.
  So if the temperature is the same during 12 hours, I have no value during 12 hours.
  It means thet temperature of the 2 rooms is not reported at the same time.
  With google chart I have to do something like:</p>
  
  <ul>
  <li>time, temp_room1,temp_room2</li>
  <li>08:01AM, 19, 20</li>
  <li>10:33AM, 18, 20</li>
  <li>11:00AM, 18, 21</li>
  </ul>
  
  <p>However, when I read my data, at 10:33AM I have a value reported for temp_room1 only since the temperature did not change in room2.
  So If I follow google chart rule, I have to set the temperature of room2 to the previously known temperature for this room! This is cumbersome.</p>
  
  <p>Do I have another means?
  I was thinking about this:</p>
  
  <ul>
  <li>08:01AM, 19, 20</li>
  <li>10:33AM, 18,</li>
  <li>11:00AM, , 21</li>
  </ul>
  
  <p>Which is easy for me, it is natural as it maps to the reality (the log I have out of my database).
  Any idea?</p>
  
  <p>thanks,
  rod</p>