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Global mapping of multiple categories by colour

Rhona,

I am completely unfamiliar with the package and functions you're using,
so I had supposed you would use functions from the sp and rgdal packages.
For what it's worth, I'll give an example below.

However, probably you will need to share at least a representative portion
of your data in order for people to give useful help. One way is to
include the ouput of the dput() function. In your case, probably,
  dput(data3)
or perhaps
  dput(head(data3))
if data3 is big.


Here is an example that requires that your countries be stored in a
SpatialPolygonsDataFrame. In this example, first we create some arbitrary
polygons, then plot them. It's not complete solution for your situation,
but is, I hope, analogous.

Probably, my email software will mangle the line lengths.

## example data, creating a SpatialPolygonsDataFrame
## copied from help('over',package='sp')
r1 = cbind(c(180114, 180553, 181127, 181477, 181294, 181007, 180409,
 c(332349, 332057, 332342, 333250, 333558, 333676,   180162, 180114),
                     332618, 332413, 332349))
r2 = cbind(c(180042, 180545, 180553, 180314, 179955, 179142, 179437,
  179524, 179979, 180042), c(332373, 332026, 331426, 330889, 330683,
                             331133, 331623, 332152, 332357, 332373))
r3 = cbind(c(179110, 179907, 180433, 180712, 180752, 180329, 179875,
  179668, 179572, 179269, 178879, 178600, 178544, 179046, 179110),
  c(331086, 330620, 330494, 330265, 330075, 330233, 330336, 330004,
    329783, 329665, 329720, 329933, 330478, 331062, 331086))
r4 = cbind(c(180304, 180403,179632,179420,180304),
  c(332791, 333204, 333635, 333058, 332791))
     
sr1=Polygons(list(Polygon(r1)),"r1")
sr2=Polygons(list(Polygon(r2)),"r2")
sr3=Polygons(list(Polygon(r3)),"r3")
sr4=Polygons(list(Polygon(r4)),"r4")
sr=SpatialPolygons(list(sr1,sr2,sr3,sr4))
srdf=SpatialPolygonsDataFrame(sr, data.frame(cbind(1:4,5:2),
row.names=c("r1","r2","r3","r4")))


## now plot
plot(srdf)
plot(srdf,col=1:4)