title: Adding State abbreviations to map generated using ggplot2
body: <p>I am trying to add state abbreviations to a US map generated using ggplot2 and having some difficulties with it. I believe the "fill = " option is causing it, but I am not sure.</p>
  
  <p>Below I provide the code I am using. Initially, I generate the map the way I want except for the state names. Next, I try to overlay state abbreviations on the same map. </p>
  
  <p>Unfortunately it is not working out for me. If I comment out "fill = " option from the first map, I can generate a map with state abbreviations. But that map does not show what I intend to show. I have tried several ways. I am just leaving one option in the code for the moment.</p>
  
  <p>To add the state abbreviations, I am following some of the suggestions I have read in this forum. In particular, I am trying to follow the advice from a discussion titled "ggplot centered names on a map" dated February 25, 2012.</p>
  
  <p>I would appreciate any help on how I can add/overlay the state abbreviations to the first map.</p>
  
  <pre><code># Master US location data
  states &lt;- map_data("state")
  
  # Read in the data
  rate &lt;- read.csv("~/R/HealthCare/Data/Test_data.csv")
  
  names(rate) &lt;- tolower(names(rate))
  rate$numer &lt;- as.factor(rate$numer)
  rate$region &lt;- tolower(rate$statename)
  
  
  # Create data for US mapping
  tomap &lt;- merge(states, rate, sort = FALSE, by = "region")
  tomap &lt;- tomap[order(tomap$order), ]
  
  
    ## US Map
  
   # 1. Target Map (w/o state abbr)
  p &lt;- qplot(long, lat, data = tomap, 
              group = group, 
              fill = numer,
              geom = "polygon")
  
  p + scale_fill_brewer(palette = "Greens",
                      guide = guide_legend(reverse = TRUE),
                      labels = c("1st cat", "2nd cat", 
                                 "3rd cat", "4th cat")) 
  
  
  
    # 2. Add State Abbreviations to Target Map
  stannote &lt;- aggregate(cbind(long, lat, group, numer) ~ stateabbr, data = tomap, 
                        FUN=function(x)mean(range(x)))
  
  
  q &lt;-  qplot(long, lat, data = tomap, 
              group = group,
              #fill = numer,
              fill = "red", #testing
              geom = "polygon") +
    geom_text(data=stannote, aes(long, lat, label = stateabbr), color = "blue", size=3) +
    coord_map()
  
  q
  </code></pre>
  
  <p>The sample data file looks like the following –</p>
  
  <pre><code>StateName,StateAbbr,Numer
  Alabama,AL,0
  Alaska,AK,0
  Arizona,AZ,0
  Arkansas,AR,0
  California,CA,0
  Colorado,CO,0
  Connecticut,CT,0
  Delaware,DE,0
  District of Columbia,DC,1
  Florida,FL,0
  Georgia,GA,0
  Hawaii,HI,0
  Idaho,ID,1
  Illinois,IL,0
  Indiana,IN,0
  Iowa,IA,1
  Kansas,KS,0
  Kentucky,KY,1
  Louisiana,LA,1
  Maine,ME,2
  Maryland,MD,0
  Massachusetts,MA,2
  Michigan,MI,0
  Minnesota,MN,1
  Mississippi,MS,0
  Missouri,MO,0
  Montana,MT,0
  Nebraska,NE,0
  Nevada,NV,1
  New Hampshire,NH,1
  New Jersey,NJ,2
  New Mexico,NM,1
  New York,NY,3
  North Carolina,NC,0
  North Dakota,ND,1
  Ohio,OH,0
  Oklahoma,OK,0
  Oregon,OR,2
  Pennsylvania,PA,0
  Rhode Island,RI,0
  South Carolina,SC,0
  South Dakota,SD,1
  Tennessee,TN,0
  Texas,TX,0
  Utah,UT,1
  Vermont,VT,2
  Virginia,VA,0
  Washington,WA,2
  West Virginia,WV,0
  Wisconsin,WI,0
  Wyoming,WY,0
  </code></pre>