title: Plotting Thematic Maps in R Using Shapefiles and Data Files from DIfferent Sources
body: <p>Given a shapefile, how do I shape and use a data file in order to be able to plot thematic maps using identifiers that correspond to shape regions in the shapefile?</p>
  
  <pre><code>#Download English Government Office Network Regions (GOR) from:
  #http://www.sharegeo.ac.uk/handle/10672/50
  tmp_dir = tempdir()
  url_data = "http://www.sharegeo.ac.uk/download/10672/50/English%20Government%20Office%20Network%20Regions%20(GOR).zip"
  zip_file = sprintf("%s/shpfile.zip", tmp_dir)
  download.file(url_data, zip_file)
  unzip(zip_file, exdir = tmp_dir)
  
  library(maptools)
  
  #Load in the data file (could this be done from the downloaded zip file directly?
  gor=readShapeSpatial(sprintf('%s/Regions.shp', tmp_dir))
  
  #I can plot the shapefile okay...
  plot(gor)
  
  #and I can use these commands to get a feel for the data...
  summary(gor)
  attributes(gor@data)
  gor@data$NAME
  #[1] North East               North West              
  #[3] Greater London Authority West Midlands           
  #[5] Yorkshire and The Humber South West              
  #[7] East Midlands            South East              
  #[9] East of England         
  #9 Levels: East Midlands East of England ... Yorkshire and The Humber
  
  #download data from http://www.justice.gov.uk/downloads/publications/statistics-and-data/courts-and-sentencing/csq-q3-2011-insolvency-tables.csv
  #insolvency&lt;- read.csv("~/Downloads/csq-q3-2011-insolvency-tables.csv")
  insolvency=read.csv("http://www.justice.gov.uk/downloads/publications/statistics-and-data/courts-and-sentencing/csq-q3-2011-insolvency-tables.csv")
  insolvencygor.2011Q3=subset(insolvency,Time.Period=='2011 Q3' &amp; Geography.Type=='Government office region')
  #tidy the data
  require(gdata)
  insolvencygor.2011Q3=drop.levels(insolvencygor.2011Q3)
  
  names(insolvencygor.2011Q3)
  #[1] "Time.Period"                 "Geography"                  
  #[3] "Geography.Type"              "Company.Winding.up.Petition"
  #[5] "Creditors.Petition"          "Debtors.Petition"  
  
  levels(insolvencygor.2011Q3$Geography)
  #[1] "East"                     "East Midlands"           
  #[3] "London"                   "North East"              
  #[5] "North West"               "South East"              
  #[7] "South West"               "Wales"                   
  #[9] "West Midlands"            "Yorkshire and the Humber"
  
  #So what next?   
  </code></pre>
  
  <p>Having got that far, how do I take the next step in generating a thematic/choropleth map, that colours each region according to the the Debtors.Petition value, for example?</p>
  
  <p>(I also just noticed a possible gotcha - there is a mismatch in the capitalisation GOR levels: "Yorkshire and the Humber" and "Yorkshire and The Humber" )</p>