title: R - colouring specific countries in a spatial polygon
body: <p>How does one colour in a subset of regions (e.g. only "Magugu" and "Nkaiti) as identified by the <code>$Name_3</code> field in a spatial polygon? I played around with <code>plot()</code> and a subset-vector, but without success. Many thanks in advance, W</p>
  
  <pre><code>Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots
    ..@ data       :'data.frame': 2800 obs. of  14 variables:
    .. ..$ PID      : int [1:2800] 97867 97868 97869 97870 97871 97872 97873 97874 97875 97876 ...
    .. ..$ ID_0     : int [1:2800] 225 225 225 225 225 225 225 225 225 225 ...
    .. ..$ ISO      : chr [1:2800] "TZA" "TZA" "TZA" "TZA" ...
    .. ..$ NAME_0   : chr [1:2800] "Tanzania" "Tanzania" "Tanzania" "Tanzania" ...
    .. ..$ ID_1     : int [1:2800] 12 12 12 12 12 12 12 12 12 12 ...
    .. ..$ NAME_1   : chr [1:2800] "Manyara" "Manyara" "Manyara" "Manyara" ...
    .. ..$ ID_2     : int [1:2800] 52 52 52 52 52 52 52 52 52 53 ...
    .. ..$ NAME_2   : chr [1:2800] "Babati" "Babati" "Babati" "Babati" ...
    .. ..$ ID_3     : int [1:2800] 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 ...
    .. ..$ NAME_3   : chr [1:2800] "Magugu" "Mamire" "Mwada" "Nkaiti" ...
    .. ..$ NL_NAME_3: chr [1:2800] "" "" "" "" ...
    .. ..$ VARNAME_3: chr [1:2800] "" "" "" "" ...
    .. ..$ TYPE_3   : chr [1:2800] "Division" "Division" "Division" "Division" ...
    .. ..$ ENGTYPE_3: chr [1:2800] "Division" "Division" "Division" "Division" ...
    ..@ polygons   :List of 2800
  </code></pre>