title: How to add routes (polylines) between two markers in leaflet
body: <p>I wish to add the polyline between these two point. How can I do this?</p>
  
  <pre><code>m &lt;- leaflet() %&gt;%
       addPolylines() %&gt;%
       addTiles() %&gt;%  # Add default OpenStreetMap map tiles
       addMarkers(lng = -87.6266382, lat = 41.8674336,
                  popup = "starting") %&gt;%
       addMarkers(lng = -87.64847, lat = 41.9168862,
                  popup = "Destination")
  
  m  # Print the map
  </code></pre>
  
  <p>Example of the data.</p>
  
  <pre><code>| region      | from_lat   | from_long    | to_lat      | to_long    |
  |-------------|------------|------------- |-------------|----------- |
  | 1           | 41.8674336 | -87.6266382  | 41.887544   | -87.626487 |
  | 2           | 41.8674336 | -87.6266382  | 41.9168862  | -87.64847  |
  | 3           | 41.8674336 | -87.6266382  | 41.8190937  | -87.6230967|
  </code></pre>