On Thu, 15 Mar 2007, Adrian Baddeley wrote: > > On Tue, 13 Mar 2007, Michael Friendly wrote: > > > I've read the documentation, but can't find an example of how > > to specify a circular window for the ppp object that would contain the > > data and the window. > > To create a circular window in spatstat, you can use the > function disc(). See help(disc). > > For example suppose a point pattern with coordinates x, y (two vectors) > is observed inside a pot with centre (x0, y0) and radius R. > Then > pot <- disc(R, c(x0,y0)) > creates a window (owin object) representing the pot, > and > X <- ppp(x, y, window=pot) > creates the point pattern. > > Since spatstat always plots spatial objects isometrically, you can also > use plot(disc(....)) just to draw a circle. > > > The data structure is something like a data frame for all the > > germinating seeds, recording (X,Y) location and maybe some other > > measure like size after xx days: > > > > PotID Treatment SeedType X Y size > > Currently, a point pattern can only have one mark variable > (e.g. you can attach the SeedType to each point, or attach the size to > each point, but not both). > This will change in spatstat version 2 which will be released soon. > > > (Is there something better?) > > There is nothing better than spatstat! %^]
Great! To get to the sp Polygon object: res0 <- disc(1, c(0,0))$bdry res <- Polygon(rbind(res0, res0[1,])) should anyone need it. Roger > > regards > Adrian Baddeley > -- Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: [EMAIL PROTECTED] _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
