title: Small ggplot2 plots placed on coordinates on a ggmap
body: <p>I would like to first use ggmap to plot a specific area with longitude and latitude as axes.</p>
  
  <p>Then I would like to put small ggplot2 plots on the specific locations, given their longitude and latitude. These can be barplots with minimal theme. </p>
  
  <p>My database may have the columns:</p>
  
  <pre><code>1. town
  2. longitude
  3. latitude
  4. through 6. value A, B, C
  </code></pre>
  
  <p>I generate a plot (pseudocode)</p>
  
  <pre><code>p &lt;- ggmap(coordinates) 
  </code></pre>
  
  <p>and I have my minimal ggplot2 design </p>
  
  <pre><code>q&lt;-ggplot2()+geom_bar(....)+ ... x-axis null y axis null minimal template
  </code></pre>
  
  <p>How to combine the two designs to have a ggmap with small minimal ggplot plots imposed on specific coordinates of the map? </p>