title: Pandas Pyplot Multiple Markers, same line
body: <p>I have a df:</p>
  
  <pre><code>time    c_1    c_2   c_3
   t1      v1    NaN    t1
   t2      v2    NaN    NaN   
   t3      v3    t3     NaN 
   t4      v4    NaN    NaN 
   t5      v5    t5     NaN 
   t6      v6    NaN    t6
  </code></pre>
  
  <p>How do you:</p>
  
  <ol>
  <li>Use matplotlib.pyplot to plot a line (t1, c_1)</li>
  <li>And marks every corresponding point in (c_2) on the line in a particular style (say, green)</li>
  <li>And also mark every point in (c_3) on the same line in another style (say, blue)</li>
  <li>Then draw a dotted line to connect the markers (t1, t3), t3, t6) and (t5, t6)</li>
  </ol>
  
  <p>I broke the questions down into points so that it is easier to read, but essentially I'm very new to pyplot, and I can't find a way to style 2 different markers in the same syntax. I'm also not very sure how to manipulate the markers, if that even possible..</p>
  
  <p>What is the 'usual' way to accomplish this?</p>