On Fri, 10 Jun 2005, Roger Bivand wrote: > On Thu, 9 Jun 2005, David Forrest wrote: > > > I have some disconnected boundary data from a finite element ocean model > > and I'd like to make a plot. > > > > Maptools looks promising, but since my data is not in a shapefile or a > > map, I'm unclear on what the best way to approach the problem. > > If the line segments are unconnected, you will first need to establish > (short) lists saying which segments (in which order and direction) bound > each polygon to be filled with colour when plotting. A package you can > consider for "rolling your own" spatial rings is sp, which is on CRAN.
The segments are largely connected -- my domain is bounded by a list of open boundary segments, land boundary segments, and several islands. library(sp) looks like the proper tool. > Once you have the list describing segment membership, order and direction > for each ring, building a SpatialRings object is not difficult. The hard > bit is going from spaghetti line segments to the list imposing order. > > Alternatively, the PBSmapping package may have suitable functions for > coersing polySet objects into rings. If your coordinates were in the > Pacific, I'd say PBSmapping might already have what you need, but your > example coordinates are Atlantic. > > (Could I suggest moving this discussion to R-sig-geo, referenced in the > "Spatial" Task View on CRAN (top left corner in navigation bar)? Sure. I just subscribed. How do you find the Task Views? I found the mailing list off of http://www.r-project.org/ -- Mailing Lists and the CRAN link brings up mirrors. Doh! I just answered my own question; these are different: http://www.r-project.org/ http://cran.r-project.org/ I thought they were simple mirrors of the homepage for downloading, but the menus are different. The page at http://cran.r-project.org/ Task Views / Spatial http://cran.r-project.org/src/contrib/Views/Spatial.html looks like just what I need. Thanks again. > > > > >geom[1:10,] > > lon lat depth > > 1 -75.42481 35.58192 16.172 > > 2 -75.40726 35.58567 18.045 > > 3 -75.41351 35.60312 17.333 > > 4 -75.38888 35.58959 20.787 > > 5 -75.39495 35.60706 19.834 > > 6 -75.36964 35.59370 20.950 > > 7 -75.37556 35.61159 20.941 > > 8 -75.35530 35.61660 23.107 > > 9 -75.34950 35.59800 22.960 > > 10 -75.33418 35.62194 23.934 > > > > >island1<-c(2,3,4,2) > > >water<-c(1,3,5,7,8,10) > > > land<-c(1,2,4,6,9,10) > > > plot(geom$lon[land],geom$lat[land],pch='.',t='l') > > lines(geom$lon[water],geom$lat[water],pch='.',t='l',col="blue") > > lines(geom$lon[island1],geom$lat[island1],pch='.',t='l',col="green") > > > > The above is toy-sized: dim(geom) is on the order of 120000,3 and there > > are about 30 different islands. Maptools seems devoted to shapefiles, > > and it is unclear how to create 'polylists'. > > > > Is there a good way to manage and graph data defined on irregular grids? > > > > Dave Dave -- Dr. David Forrest [EMAIL PROTECTED] (804)684-7900w [EMAIL PROTECTED] (804)642-0662h http://maplepark.com/~drf5n/ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html