title: Plot county names on faceted state map (ggplot2)
body: <p>I am working through making cholorpleth's (a learning project I started <a href="http://www.talkstats.com/showthread.php/23324-An-R-learning-project-%28feel-free-to-learn-with-me%29?p=82292&amp;viewfull=1#post82292" rel="nofollow noreferrer">HERE</a>).  I once asked about plotting text on a map (<a href="https://stackoverflow.com/questions/9441778/improve-centering-county-names-ggplot-maps">HERE</a>) on SO.  I'm now trying to plot names on the same map but with it faceted but keep getting an error:</p>
  
  <pre><code>Error in eval(expr, envir, enclos) : object 'group' not found
  </code></pre>
  
  <p>Which I take to me that R hates me and I'm an imbecile :)  <code>traceback</code> is ~ 5 miles long so that's not a help either.  If you take out the <code>geom_text</code>  everything runs fine.</p>
  
  <p>PS I know about the new <code>geom_map</code> and have been playing with that as well but this is a separate problem that's bugging me.</p>
  
  <p>Thank you in advance for your help.</p>
  
  <pre><code>#Load three data sets from my dropbox 
  load(url("http://dl.dropbox.com/u/61803503/Names/cholo.RData"))
  
  #view head of the three data frames
  lapply(list("map.data2"=map.data2, "ny"=ny, "centroids"=centroids), head)
  ####################################################################
  # map.data2 contains the filling information (test scores)         #
  # ny contains the lat and long information for plotting boundaries #
  # centroids contains the information for plotting labels           #
  ####################################################################
  
  #Load Necessary Libraries
  library(ggplot2); library(maps); library(RColorBrewer); library(scales)
  
  ggplot(map.data2, aes(long, lat, group=group)) +  #plot pass rates math
     geom_polygon(aes(fill=level), colour=alpha('white', 1/2), size=0.2) +
     geom_polygon(data=ny, colour='black', fill=NA) + 
     scale_fill_brewer(palette='RdYlBu', guide = guide_legend(title = 
         "Percent Passing"))+
     facet_grid(.~Subject)+
     #annotate(data = "text", label = centroids$subregion, x = centroids$long, 
     #    y = centroids$lat, size = 2, colour = "black") +
     geom_text(data=centroids, aes(x=long, y=lat, 
         label=subregions, angle=angle), size=3) +
     opts(title = "
         New York State Counties Passing Rate \non Elementary ELA Assessments") +
     opts(axis.text.x = theme_blank(), axis.text.y = theme_blank(), 
         axis.ticks = theme_blank())+
     opts(legend.background = theme_rect()) +
     scale_x_continuous('') + scale_y_continuous('') + 
     labs(title = "legend title") + theme_bw()+
     opts(axis.line=theme_blank(),axis.text.x=theme_blank(),
          axis.text.y=theme_blank(),axis.ticks=theme_blank(),
          axis.title.x=theme_blank(), legend.position="bottom",
          axis.title.y=theme_blank(),
          panel.background=theme_blank(),panel.grid.major=theme_blank(),
          panel.grid.minor=theme_blank(),plot.background=theme_blank())
  </code></pre>