[R-sig-Geo] readShapePoly function and putting text on map

Wang, Kevin (SYD) kevinwang at kpmg.com.au
Thu Dec 16 11:31:11 CET 2010

Thanks, Roger,

Got it to work. 

Got another question, is it possible to "enlarge" the map either using the plot function, or another function?



sent from my hTC Desire handset

----- Reply message -----
From: "Roger Bivand" <Roger.Bivand at nhh.no>
Date: Thu, Dec 16, 2010 9:22 pm
Subject: [R-sig-Geo] readShapePoly function and putting text on map
To: "Wang, Kevin (SYD)" <kevinwang at kpmg.com.au>
Cc: "r-sig-geo at r-project.org" <r-sig-geo at r-project.org>, "Kevin Wang" <wang.kevin at gmail.com>

On Thu, 16 Dec 2010, Wang, Kevin (SYD) wrote:

> Hi all,
> I've managed to draw a map using the following code:
> 	lga1 <- readShapePoly("D:/Documents and Settings/kevinwang/My
> Documents/SMS/ASGC/LGA10aAust", IDvar = "LGA_CODE10")
> 	plot(lga1[lga1$STATE_CODE == 7,], border="blue")
> 	title(main = "NT LGA Division")
> 	text(coordinates(lga1[lga1$STATE_CODE == 7,]), labels =
> sapply(slot(lga1[lga1$STATE_CODE == 7,], "polygons"),
> function(i) slot(i, "ID")), cex=0.6)
> This gives me a map of Northern Territory (Australia), with local
> government division LGA and the code for the LGAs in each LGA.
> However, instead of the LGA code, I'm trying to use LGA names (which is
> in a variable called LGA_NAME10) instead.  But when I tried to change
> the IDvar I got:
> 	> lga1 <- readShapePoly("D:/Documents and Settings/kevinwang/My
> Documents/SMS/ASGC/LGA10aAust", IDvar = "LGA_NAME10")
> 	Error in `row.names<-.data.frame`(`*tmp*`, value = c("Albury
> (C)", "Armidale Dumaresq (A)",  :
> 	  duplicate 'row.names' are not allowed
> 	In addition: Warning message:
> 	non-unique value when setting 'row.names': 'Campbelltown (C)'
> My guess is that there are duplicated names in LGA_NAME10 variable.  So
> I'm wondering if it's possible to specify "LGA_NAME10" in the text()
> function instead?

         lga1_7 <- lga1[lga1$STATE_CODE == 7,]
         plot(lga1_7, border="blue")
         title(main = "NT LGA Division")
             labels = as.character(lga1_7$LGA_NAME10), cex=0.6)

(above you could have said labels=rownames(lga1)[lga1$STATE_CODE == 7], 
the example on the help hasn't been updated, but will be now - thanks 
for reminding me).


> Thanks in advance for the help!
> Cheers
> Kevin
> Kevin Wang
> Senior Adviser, Government Advisory Services
> Advisory
> 10 Shelley Street
> Sydney  NSW  2000  Australia
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> Fax	+61 2 9335 7001
> Mob	0404 518 301
> kevinwang at kpmg.com.au <mailto:kevinwang at kpmg.com.au >
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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no


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