title: How to add vertical line between 2 markers in R plotly?
body: <p>I just started using plotly in R, and I've made a plot like this
  <a href="https://i.stack.imgur.com/PtErG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PtErG.png" alt="enter image description here" /></a>
  with a syntax like this:</p>
  <pre><code>      maximum &lt;- rnorm(30, mean = 20)
    datasource &lt;- rnorm(30, mean = 15)
    minimum &lt;- rnorm(30, mean = 10)
    x &lt;- c(1:30)
    
    data &lt;- data.frame(x,datasource,maximum,minimum)
    
    fig &lt;- plot_ly(data, x = ~x, y = ~datasource, name = 'trace 1', type = 'scatter', mode = 'lines+markers', marker = list(size = 10))
    fig &lt;- fig %&gt;% add_trace(y = ~maximum, name = 'maximum', mode = 'markers', marker = list(size = 10))
    
    fig &lt;- fig %&gt;% add_trace(y = ~minimum, name = 'minimum', mode = 'markers', marker = list(size = 10)) 
    
    fig &lt;- fig %&gt;% layout(title = &quot;XBAR CHART&quot;,
                          xaxis = list(title = &quot;ID&quot;),
                          yaxis = list (title = &quot;Measurement Value (mm)&quot;))
    fig
  </code></pre>
  <p>I want to add a line connecting the minimum and maximum markers like the following.
  <a href="https://i.stack.imgur.com/Lkmk9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Lkmk9.png" alt="enter image description here" /></a></p>
  <p>I've been trying but haven't found the solution.</p>
  <p>I hope I find a solution here.
  thanks</p>