Hi Paul, You're missing the group specification:
ggplot(dum, aes(x = long, y = lat)) + geom_path(aes(group = group)) Hadley On Tue, Apr 27, 2010 at 4:17 AM, Paul Hiemstra <p.hiems...@geo.uu.nl> wrote: > Hi people, > > I have a question regarding plotting a SpatialPolygonsDataFrame using > ggplot2. To convert the SPDF to a dataframe with the coordinates I already > use the excellent solution provided by Hadley in: > > http://tolstoy.newcastle.edu.au/R/e6/help/09/03/8668.html > > Some example code: > > library(maptools) > library(ggplot2) > x <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1], > IDvar="FIPSNO", proj4string=CRS("+proj=longlat +ellps=clrk66")) > dum = fortify(x, region = "CNTY_ID") > ggplot(dum, aes(x = long, y = lat)) + geom_path() > > My problem is that not only the counties are drawn, but also lines between > the end point of one countie polygon and the beginning of the next. I solve > this right now by adding the counties I want to plot one by one using: > > p + geom_path(subset(dum, id == 1) + geom_path(subset(dum, id == 2) + ... > etc > > This is of course a solution, but not an elegant one. Creating a new ggplot > object like: > > unique_ids = unique(dum$id) > bla = ggplot(subset(dum, id == unique_ids[1]), aes(x =long, y = lat)) + > geom_path() > for(id in unique_ids[2:length(unique_ids)]) { > bla = bla + layer(data = subset(dum, id == id), mapping = aes(x =long, > y = lat), geom = "path") > } > print(bla) > Has exactly the same problem as using ggplot(dum, aes(x = long, y = lat)) > + geom_path(). I browsed the net and the maling list and could not find the > answer, only references to the fortify() solution of Hadley. > > Anybody have an idea for an elegant solution to the problem? > > cheers, > Paul > > -- > Drs. Paul Hiemstra > Department of Physical Geography > Faculty of Geosciences > University of Utrecht > Heidelberglaan 2 > P.O. Box 80.115 > 3508 TC Utrecht > Phone: +3130 274 3113 Mon-Tue > Phone: +3130 253 5773 Wed-Fri > http://intamap.geo.uu.nl/~paul > http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770 > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Assistant Professor / Dobelman Family Junior Chair Department of Statistics / Rice University http://had.co.nz/ _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
