title: plotly in r 3d arrows between two points
body: <p>I would like to draw arrows between two points. This is the problem, where I made the three arrows with a graphical program to explain my problem.</p>
  
  <p><img src="https://i.stack.imgur.com/gmIwO.png" alt="enter image description here"></p>
  
  <p>That is my source code:</p>
  
  <pre><code>require(plotly)
  
  a &lt;- c(5,16,16,17,18,23,25,27,37,42,5)
  b &lt;- c(13,12,26,15,14,6,10,22,14,25,17)
  c &lt;- c(12,14,25,26,8,9,27,30,31,26.5,12)
  
  ap &lt;- c(5,12,16,17,11,23,25,27,37,21.5,5)
  bp &lt;- c(13,12,26,15,14,6,10,22,14,12.5,17)
  cp &lt;- c(12,14,25,26,8,9,27,30,31,26,12)
  
  rnn &lt;- c("U1", "U2", "U3", "U4", "U5", "U6", "U7", "U8", "U9", "U10", "U11")
  
  m &lt;- list( symbol = 200, size = 8, line = list( color = toRGB("yellow"), width = 2 ) ) 
  m1 &lt;- list( symbol = "triangle", color="black", sizemod = "diameter", size = 5, line = list( color = "black", width = 2 ) )
  
  plot_ly(x = ap, y = bp, z = cp) %&gt;%
  
    add_trace(marker = m1, type = "scatter3d", mode = "text+markers", 
          name = "projected", linetypes = NULL, text = rnn) %&gt;%
    add_trace(x = a, y = b, z = c, marker = m, type = "scatter3d", mode = "text+markers", 
          name = "original", linetypes = NULL, text = rnn) 
  </code></pre>
  
  <p>Many thanks.</p>