Look at the spsample function in the sp package. If you can convert the information on your contour(s) into a spatial line object, then spsample can help with choosing random points along that line/contour. That may accomplish what you want.
On Wed, Oct 9, 2013 at 5:32 AM, Seth Bigelow <[email protected]> wrote: > Hello all: > > > > I wish to place sampling plots at regular elevation intervals up a > mountain. > Plot centers should be placed at random within a 100 m wide transect along > the contour. Can anyone suggest an efficient way of doing this? Code below > places plots on a single transect on the volcano dataset, but does not do > the 'along the contour' randomization. > > > > Appreciatively, Seth Bigelow > > > > library(sp) > > library(maptools) > > library(rgeos) > > > > data(volcano) > > v.sldf <- ContourLines2SLDF(contourLines(volcano)) > > t.mtx <- cbind(x=c(1,0.35),y=c(0,0.55)) > > t.sl <- SpatialLines(list(Lines(Line(t.mtx), ID='1'))) > > sample.sp <- gIntersection(v.sldf,t.sl) > > plot(v.sldf, axes=TRUE) > > plot(sample.sp, pch=21,add=T) > > > > ## End ## > > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > [email protected] > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Gregory (Greg) L. Snow Ph.D. [email protected] [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
