R help - Apr 2009 - political maps world maps in R, wrld_simpl

dear all,
I'm a newbie in map tools. I was asking to perform an apparently very
simple task.
I have a list of countries (about fifty all over in the world) scored
with a real positive value. Eg

Country score
Italy   .56
UK      .58
Korea   .41
Mexico  .63
...

I wish to plot geographical maps where every country is filled with a
color depending on his score.

Using maptools library and wrld_simpl I can easily perform the world
map. Here my code:

#########################################################
###    plot the world map

patramp = colorRamp(c(rgb(0,0,.7),"red"))# my personal ramp color
palette

library(maptools)
load(url("http://spatial.nhh.no/R/etc/TM_WORLD_BORDERS_SIMPL-0.2.RData"))

country2    = c("Albania", "Argentina",
"Australia", "Austria", "Belgium",
"Belarus", "Brazil", "Bulgaria",
"Canada", "China", "Colombia",
"Croatia", "Denmark", "Egypt",
"United.Arab.Emirates", "Estonia",
"Philippines", "Finland", "France",
"Germany", "Japan", "Jordan",
"Greece", "India", "Indonesia", "Iran",
"Ireland", "Israel",
"Italy", "Latvia", "Libya", "Lithuania",
"Malaysia", "Mexico",
"Morocco", "Norway", "Netherlands",
"Pakistan", "Poland", "Portugal",
"United.Kingdom", "Czech.Republic", "Romania",
"Russia", "Serbia",
"Singapore", "Syrian.Arab.Republic",
"Slovak.Republic", "Slovenia",
"Spain", "United.States", "South.Africa",
"Korea.South", "Sweden",
"Switzerland", "Thailand",
"Taiwan.Province.of.China", "Tunisia",
"Turkey", "Ukraine", "Hungary",
"Venezuela", "Vietnam") # The my
countries' names

country.all = wrld_simpl$NAME # countries' names as coded in wrld_simpl
n.all       = length(country.all)
col.map     = numeric(n.all)

# grep country2 in country.all
for (i in 1:length(country2)){
  col.map[grep(country2[i],country.all)] = runif(1) # assign a random
score to country i
}
# it certainly exists a cleaner coding for this but it's not my first
thought now

c2      = col.map!=0    # set countries with score != 0 is not listed
in country2
col.map2=col.map
col.map2[!c2]=rgb(.95,.96,.97)  # be grey the countries not listed in
country2 object
col.map2[c2]= rgb(patramp(col.map[c2])/255) # ramp the remaining
plot(wrld_simpl,col=col.map2,axes=T) # nice plot

###   end of program
#########################################################

Now what if I wish to zoom on some sub world regions such as Eastern
Europe or America or any other user defined contiguous sub group?

Russia is a large country I could be interested in cutting it in two
peaces eastern and western. Can I do it using wrld_simpl or should I
search for other data? If so where can I find free maps data?

Some documentation exists but it seems sparse to me.
Any hints will be appreciated.
Thanks in advance,

Patrizio

Patrizio Frederic <frederic.patrizio <at> gmail.com> writes:
> 
> dear all,
> I'm a newbie in map tools. I was asking to perform an apparently very
> simple task.
> I have a list of countries (about fifty all over in the world) scored
> with a real positive value. Eg
> ...
> 
> I wish to plot geographical maps where every country is filled with a
> color depending on his score.
> Using maptools library and wrld_simpl I can easily perform the world
> map. 
Note that the file is included in recent releases of maptools, so just say 

data(wrld_simpl)
> library(maptools)
>
load(url("http://spatial.nhh.no/R/etc/TM_WORLD_BORDERS_SIMPL-0.2.RData"))
For matching the countries you have with the countries in the object (note
that names may differ), I suggest simply adding ISO3 codes to your data 
frame, and using them as row names as well. Look at the spCbind methods in
maptools.
> Now what if I wish to zoom on some sub world regions such as Eastern
> Europe or America or any other user defined contiguous sub group?
Either select using [ or plot using xlim/ylim arguments
> 
> Russia is a large country I could be interested in cutting it in two
> peaces eastern and western. Can I do it using wrld_simpl or should I
> search for other data? If so where can I find free maps data?
You can plot part of Russia with the object as it is by using xlim/ylim
arguments. You can manipulate low-level objects if you need to, but
it is not easy unless you know what you are doing.
> 
> Some documentation exists but it seems sparse to me.
The R-sig-geo list is more focussed on this kind of question, as is pointed 
out on the Spatial Task View on CRAN. 

Hope this helps,

Roger Bivand
> Any hints will be appreciated.
> Thanks in advance,
> 
> Patrizio