title: Labelling points on world map in ggplot2
body: <p>I have created a world map with the use of the ggplot2 library.</p>
  
  <p><img src="https://i.stack.imgur.com/fGXl9.png" alt="Map"></p>
  
  <p>I am attempting to label the two cities (Shanghai and Sao Paulo) respectively through using labels in ggplot2. However, when I try to add labels I get the error message:</p>
  
  <pre><code>Warning: Ignoring unknown aesthetics: labels
  Error: geom_text requires the following missing aesthetics: x, y, label
  </code></pre>
  
  <p>Here is the full code:</p>
  
  <pre><code>require(maps)
  require(mapdata)
  library(ggplot2)
  
  countries = c("Sao Paulo","Shanghai")
  
  global &lt;- map_data("world")
  ggplot() + geom_polygon(data = global, aes(x=long, y = lat, group = 
  group)) + 
    coord_fixed(1.3)
  
  ggplot() + 
    geom_polygon(data = global, aes(x=long, y = lat, group = group), 
  fill = NA, color = "red") + 
    coord_fixed(1.3)
  
  gg1 &lt;- ggplot() + 
    geom_polygon(data = global, aes(x=long, y = lat, group = group), 
  fill = "green", color = "blue") + 
    coord_fixed(1.3)
  gg1
  
  labs &lt;- data.frame(
    long = c(-46.625290,121.4580600),
    lat = c(-23.533773,31.2222200),
    stringsAsFactors = FALSE
  )  
  
  gg1 + 
    geom_point(data = labs, aes(x = long, y = lat), color = "red", size 
  = 5) + ggtitle("World Map") + geom_text(aes(labels=countries),vjust=0, 
  colour="red")
  </code></pre>
  
  <p>Clearly, I'm using ggplot wrong in some way but can't figure out how.</p>