title: Plotly R chart from two different dataframe
body: <p>I am trying to plot a line chart using two different <code>data.frame</code> in R using <code>plotly</code>. The problem is both <code>data.frame</code> have a different dimension. 
  Sample data for <code>data.frame</code>1:</p>
  
  <pre><code>                     DATE   SOC resdiff
   2016  2017-08-11 02:40:00 95.45    0.54
   4033  2017-08-18 02:45:00 94.88    0.56
   6048  2017-08-25 02:45:00 94.28    0.60
   8064  2017-09-01 02:45:00 93.68    0.60
   10080 2017-09-08 02:45:00 92.96    0.72
   12096 2017-09-15 02:45:00 92.13    0.83 
  </code></pre>
  
  <p>Sample data for <code>data.frame</code>2:</p>
  
  <pre><code>       data.event_type data.user          data.stamp
   1          config    *INST* 2018-06-27 14:37:29
   2          config    *INST* 2018-02-14 19:30:57
   3          config    *SYNC* 2017-12-18 07:00:53
   4          config    *SYNC* 2017-12-18 06:59:14
   5          config    *INST* 2017-10-03 00:55:25
   6          config    *INST* 2017-09-28 00:49:29
  </code></pre>
  
  <p>Line chart for <code>data.frame</code> 1:</p>
  
  <pre><code>library(plotly)
  p &lt;- plot_ly(new_res, x = ~DATE) %&gt;%
    add_trace(y = ~resdiff*100, name = 'SOC Diff',type = 'scatter',mode = 
   'lines') %&gt;%
   add_trace(y = ~SOC, name = 'SOC',type = 'scatter', mode = 'lines+markers') 
  p
  </code></pre>
  
  <p>Line chart for <code>data.frame</code> 2:</p>
  
  <pre><code>p &lt;- plot_ly(get_df[1:9,], x = ~data.stamp) %&gt;%
   add_trace(y = ~data.user, name = 'Event',type = 'scatter',mode = 'markers')
  p
  </code></pre>
  
  <p>Now problem is How to combine these two line charts into a single one? Is it possible to do by adding the <code>add_trace</code>?</p>
  
  <p>Please feel free to suggest me using <code>ggplot</code> or any other library if it will be easier.</p>