title: Add country polygons to mapbox
body: <p>I want to recreate a choropleth map with country polygons like the county level choropleth map <a href="https://plot.ly/r/county-level-choropleth/" rel="nofollow noreferrer">here</a>. And here is its result.
  <a href="https://i.stack.imgur.com/FrtDn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FrtDn.png" alt="enter image description here"></a></p>
  
  <p>I try to repeat the same procedure for a world map</p>
  
  <pre><code>library(ggplot2)
  library(dplyr)
  library(maps)
  WorldData &lt;- map_data('world') %&gt;% filter(region != "Antarctica") %&gt;% fortify
  
  Country&lt;-c("United States","Canada","France","Italy","Turkey","United States","Canada","France","Italy","Turkey")
  Val&lt;-c(50,67,89,567,9,50,67,89,567,9)
  Name&lt;-c('AD',"FGH","BGH","FGFG","EWRW",'ADy',"FGyH","BGyH","FGFyG","EyWRW")
  Test&lt;-data.frame(Country,Val,Name)
  V1 &lt;- aggregate(Val~Country,Test,sum)
  
  
  colnames(WorldData)[5]&lt;-"Country"
  m2 &lt;- data.frame(merge(V1,WorldData , by=c("Country"), all.x=T))
  
  
  p &lt;- m2 %&gt;%
    group_by(group) %&gt;%
    plot_mapbox(x = ~long, y = ~lat, color = ~Val1, colors = c('#ffeda0','#f03b20'),
                text = ~Country, hoverinfo = 'text', showlegend = FALSE) %&gt;%
    add_polygons(
      line = list(width = 0.4)
    ) %&gt;%
    add_polygons(fillcolor = ~Val1,
                 line = list(color = 'black', width = 0.5),
                 showlegend = FALSE, hoverinfo = 'none'
    ) %&gt;%
    layout(
      xaxis = list(title = "", showgrid = FALSE, showticklabels = FALSE),
      yaxis = list(title = "", showgrid = FALSE, showticklabels = FALSE),
      mapbox = list(
        style = 'light',
        zoom = 4,
        center = list(lat = ~median(lat), lon = ~median(long))),
      margin = list(l = 0, r = 0, b = 0, t = 0, pad = 0)
    )
  
  p
  </code></pre>
  
  <p>but I get:</p>
  
  <p><a href="https://i.stack.imgur.com/NWEUc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NWEUc.png" alt="enter image description here"></a></p>