[R-sig-Geo] Subsetting shapefile type PolyLine

[Rafael Duarte]

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: rduarte at ipimar.pt