On Wed, 17 Jan 2007, Albrecht Kauffmann wrote: > Hi all, > > I'm faced with a problem applying the sp package: The projection argument in > > readShapePoly(Shapefile,proj4string="CRS class argument") > > e.g.: CRS("+proj=aea +lat_1=46 +lat_2=73 +lat_0=60 +lon_0=84 +x_0=0 > +y_0=0 +ellps=clrk66 +units=m +no_defs") > > doesn't have any impact on the plotted object. I also tested the simple > example: > > xy = cbind(x = 2 * runif(100) - 1, y = 2 * runif(100) - 1) > plot(SpatialPoints(xy, proj4string = > CRS("+proj=longlat")),xlim=c(-1,1),ylim=c(-1,1)) > > looks exactly like > > plot(SpatialPoints(xy, proj4string =CRS("+proj=stere +lon_0=98 +over")) > > or > > plot(SpatialPoints(xy)) > > without any projection. > > What I'm doing wrong?
What impact would you like? The vertical scaling adjustment for geographical coordinates ("+proj=longlat") is proportional to the distance of the midpoint of ylim from the Equator, so in your case no adjustment would be expected: library(sp) set.seed(1) x <- runif(20, -10, 10) y <- runif(20, -10, 10) par(mfrow=c(3,2)) plot(SpatialPoints(cbind(x, y)), axes=TRUE) plot(SpatialPoints(cbind(x, y), proj4string=CRS("+proj=longlat")), axes=TRUE) plot(SpatialPoints(cbind(x, y+50)), axes=TRUE) plot(SpatialPoints(cbind(x, y+50), proj4string=CRS("+proj=longlat")), axes=TRUE) plot(SpatialPoints(cbind(x, y+70)), axes=TRUE) plot(SpatialPoints(cbind(x, y+70), proj4string=CRS("+proj=longlat")), axes=TRUE) par(mfrow=c(1,1)) > > I use the latest versions of sp and rgdal. > > With many thanks for any hint, > > Albrecht Kauffmann > Potsdam University > > ______________________________________________ > 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 > and provide commented, minimal, self-contained, reproducible code. > -- 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-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 and provide commented, minimal, self-contained, reproducible code.