title: Can R be used for GIS?
body: <p>I'd like to create some GIS plots, and I'm wondering if R can be used for this.  Here are some examples of plots I'd similar in concept to those I'd like to make:  </p>
  
  <ul>
  <li>A temperature plot (or contour plot) of the United States, with color (or height) determined by state GDP.  Thus, state boundaries would give discontinuities in the resulting plot.  </li>
  <li>A temperature plot of the United States where altitude is used for data.  In this case, the resulting plot should vary smoothly across state boundaries.</li>
  <li>The sum of the above 2 plots (with some scaling applied).  </li>
  </ul>
  
  <p>I'm just starting to learn R, and want to know if it would be the right tool for this kind of job.  Looking at the <a href="http://had.co.nz/ggplot2/coord_map.html">coord_map</a> of ggplot2, it looks like superimposing data onto the US is possible.  But getting data to respect state boundaries could be very difficult.  </p>
  
  <p>Any advice?</p>