[GIS] Plotting a map of New Zealand with regional boundaries in R

new-zealandr

I have been asked to make a map of New Zealand using R with regional boundaries. I need something exactly like this example of a map for Switzerland:
http://blog.revolutionanalytics.com/2009/10/geographic-maps-in-r.html

I tried copying the same commands but after I downloaded the data from gadm and tried plotting it with spplot, I ended up with ten tiny plots with New Zealand on the extreme right hand edge. I can't paste the output into this question because R will not let me save it as a file. But what I did was simply download the "level 1" data from gadm in R format and then spplot(gadm).

Please could someone help me to make a map of New Zealand showing regional boundaries, so that I can make the regions different colours? It looks like the main problems at the moment are

  1. I would like the North and South Islands to be in the middle.
  2. I don't want a super-detailed map as I would like to plot it quickly.
  3. I just want a single map, not ten of them.

Alternatively, any pointers to tutorials would be very welcome. I don't necessarily want to use the gadm data if there is a better alternative.

Best Answer

Well, I found a minimal way to answer the question but I would still be interested if people can tell me how to improve it, and I still don't understand exactly what spplot is doing. After doing a load(), I used the following commands:

nz1 <- gadm
nz1$NAME_2 <- as.factor(nz1$NAME_1)
nz1$fake.data <- runif(length(nz1$NAME_1)) 
spplot(nz1,
        "NAME_2", 
         xlim=c(163,180), 
         scales=list(draw=T), 
         ylim=c(-50,-32), 
         col.regions=rgb(nz1$fake.data, 1-nz1$fake.data, 0), 
         colorkey=F)

which produced this plot (which is the sort of thing I'm looking for): enter image description here

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