On Mon, 4 Feb 2008, Rafael Duarte wrote:
Obrigado Milton.
But:
teste2[teste2$ELEVATION == 100]
gives me an empty list. And I have data of Elevation = 100.
I also tried
teste2[teste2$ELEVATION >= 100]
teste2[teste2$ELEVATION == "100"]
But always an empty list and no plot.
Very close, with:
getinfo.shape("bat_lin")
teste2 <- readShapeLines("bat_lin")
names(teste2)
should show ELEVATION - then the help should also work. I think that the
original teste2 would say that its class() was "Map" - for the selection
with [ to work, it should be a SpatialLinesDataFrame.
read.shape is part of the infrastructure, and users are really advised to
move to sp classes, and either readShape*(), or (even better) readOGR() in
the rgdal package, for which you don't need to know in advance what kind
of shapefile you are reading.
Hope this helps,
Roger
Milton Cezar Ribeiro wrote:
Hi Rafael
i think that it could help you
teste2.elev100<-teste2[teste2$ELEVATION=100]
plot(teste2,axes=T)
plot(teste2.elev100,col=2,add=T)
Boa sorte.
Miltinho
Brazil
----- Mensagem original ----
De: Rafael Duarte <[EMAIL PROTECTED]>
Para: r-sig-geo@stat.math.ethz.ch
Enviadas: Segunda-feira, 4 de Fevereiro de 2008 8:23:08
Assunto: [R-sig-Geo] Subsetting shapefile type PolyLine
Dear all,
I am very new to SIG.
This is probably a very simple question but I could not find an answer
searching the web and the R-SIG emails archive.
I have an ESRI shapefile with a coast and bathymetric lines. In the dbf
file I have a column ?ELEVATION? that gives this information.
I import the shapefile with:
require(maptools)
teste2 <- read.shape("bat_lin")
Shapefile type: PolyLine, (3), # of Shapes: 981
Now I plot this information:
plot(teste2)
But my problem is that I want to plot a subset of bathymetric lines:
ELEVATION = 100, for example.
I tried to follow the example given in maptools: subset.
I tried to use functions: Map2lines.
But I could not find a solution to plot only a subset of bathymetric
lines.
Many thanks for any help.
Rafael
--
Rafael Duarte
Marine Resources Department - DRM
IPIMAR - National Research Institute for Agriculture and Fisheries
Av. Brasília, 1449-006 Lisbon - Portugal
Tel:+351 21 302 7000 Fax:+351 21 301 5948
e-mail: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
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