readShapePoly function and putting text on map
Thanks, Roger, Got it to work. Got another question, is it possible to "enlarge" the map either using the plot function, or another function? Cheers Kevin 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$STATE_CODE == 7,], "polygons"),
function(i) slot(i, "ID")), cex=0.6)
This gives me a map of Northern Territory (Australia), with local
government division LGA and the code for the LGAs in each LGA.
However, instead of the LGA code, I'm trying to use LGA names (which is
in a variable called LGA_NAME10) instead. But when I tried to change
the IDvar I got:
> lga1 <- readShapePoly("D:/Documents and Settings/kevinwang/My
Documents/SMS/ASGC/LGA10aAust", IDvar = "LGA_NAME10")
Error in `row.names<-.data.frame`(`*tmp*`, value = c("Albury
(C)", "Armidale Dumaresq (A)", :
duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique value when setting 'row.names': 'Campbelltown (C)'
My guess is that there are duplicated names in LGA_NAME10 variable. So
I'm wondering if it's possible to specify "LGA_NAME10" in the text()
function instead?
Maybe:
lga1_7 <- lga1[lga1$STATE_CODE == 7,]
plot(lga1_7, border="blue")
title(main = "NT LGA Division")
text(coordinates(lga1_7),
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).
Roger
Thanks in advance for the help! Cheers Kevin Kevin Wang Senior Adviser, Government Advisory Services Advisory KPMG 10 Shelley Street Sydney NSW 2000 Australia Tel +61 2 9335 8282 Fax +61 2 9335 7001 Mob 0404 518 301 kevinwang at kpmg.com.au <mailto:kevinwang at kpmg.com.au > kpmg.com.au <http://kpmg.com.au/> Best Accounting Firm - BRW Client Choice Awards 2010 Protect the environment: please think before you print [[alternative HTML version deleted]]
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