title: ggplot2 - numbered points on plot and in legend
body: <p>I'm trying to create a map with ggplot where sites are indicated using a point and a number on the map, and that numbering scheme is retained in the legend. So I'd like the first site to be labeled by a point with the number 1 in the center, and so on. Here's my code now:</p>
  
  <pre><code>library(tidyverse)
  
  # download site data
  
  dod &lt;- read_csv('https://raw.githubusercontent.com/jaymwin/fcpp_GIS/master/data/DoD_sites_latlong.csv') %&gt;%
    filter(site != 'Fort Wainwright') %&gt;%
    mutate(
      num = row_number() # my way of numbering the sites
    )
  dod
  
  # download state outlines
  
  states &lt;- map_data('state')
  
  # plot them
  
  ggplot() +
    geom_polygon(data = states, aes(long, lat, group = group), fill = 'grey95', color = 'darkgrey') +
    geom_point(data = dod, aes(x = lon, y = lat, color = site), size = 4) +
    geom_text(data = dod, aes(label = num, x = lon, y = lat), 
              size = 2, color = 'white', fontface = 'bold') +
    scale_color_manual(values = c(rep('tomato', 12)), name = 'Site') +
    labs(
      x = 'Longitude',
      y = 'Latitude'
    ) +
    theme_minimal()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/7m5UL.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7m5UL.jpg" alt="here&#39;s what the map looks like now:"></a></p>
  
  <p>Is it possible to have the map numbering scheme to correspond to the legend numbering scheme?</p>