hi,
did'nt see anything in the archive:
map('world',pro='rectangular',para=0)
yields a strange artifact (horizontal bar) extending over the whole map
at a certain latitude range (approx 65 deg. north), whereas
map('world',pro='rectangular',para=180)
(which should be the same) does not show the artifact.
the artifact shows up in other projections as well, e.g.
map('world',pro='bonne',para=45)
which seems to show that the problem might be in the data base of the
map (i.e. polygon definition)??
any ideas?
regards,
joerg
I seem to recall I came across something similar recently (well, relatively recently, perhaps a couple of years ago). The problem is related to how the code handles polygons that are split across the map boundaries. As I recall, the fix was to modify the polygons that straddle the date line. I'll have to delve into this again, but don't hold your breath, sorry. Ray Brownrigg> From: Joerg van den Hoff <j.van_den_hoff at fz-rossendorf.de> > > hi, > > did'nt see anything in the archive: > > map('world',pro='rectangular',para=0) > > yields a strange artifact (horizontal bar) extending over the whole map > at a certain latitude range (approx 65 deg. north), whereas > > map('world',pro='rectangular',para=180) > > (which should be the same) does not show the artifact. > > the artifact shows up in other projections as well, e.g. > > map('world',pro='bonne',para=45) > > > which seems to show that the problem might be in the data base of the > map (i.e. polygon definition)?? > > > any ideas? > > regards, > > joerg
There is a function recenter.Map in the TeachingDemos package that can be used with the maptools packages (rather than the maps package) to move polygons around for better looking maps. The original idea was to put the Alaskan islands on the left of the map rather than having some of them on the far right, but it also works to creat a pacific centric map or other things. It is still pretty basic as a function, if anyone wants to improve it (it could probably use a lot of improvement) they are more than welcome. Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow at intermountainmail.org (801) 408-8111> -----Original Message----- > From: r-help-bounces at stat.math.ethz.ch > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Ray Brownrigg > Sent: Wednesday, March 08, 2006 12:40 PM > To: j.van_den_hoff at fz-rossendorf.de; r-help at stat.math.ethz.ch > Subject: Re: [R] bug in map('world') ? > > I seem to recall I came across something similar recently > (well, relatively recently, perhaps a couple of years ago). > The problem is related to how the code handles polygons that > are split across the map boundaries. As I recall, the fix > was to modify the polygons that straddle the date line. I'll > have to delve into this again, but don't hold your breath, sorry. > > Ray Brownrigg > > > From: Joerg van den Hoff <j.van_den_hoff at fz-rossendorf.de> > > > > hi, > > > > did'nt see anything in the archive: > > > > map('world',pro='rectangular',para=0) > > > > yields a strange artifact (horizontal bar) extending over the whole > > map at a certain latitude range (approx 65 deg. north), whereas > > > > map('world',pro='rectangular',para=180) > > > > (which should be the same) does not show the artifact. > > > > the artifact shows up in other projections as well, e.g. > > > > map('world',pro='bonne',para=45) > > > > > > which seems to show that the problem might be in the data > base of the > > map (i.e. polygon definition)?? > > > > > > any ideas? > > > > regards, > > > > joerg > > ______________________________________________ > R-help at 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 >
> From: Joerg van den Hoff <j.van_den_hoff at fz-rossendorf.de> > > hi, > > did'nt see anything in the archive: > > map('world',pro='rectangular',para=0) > > yields a strange artifact (horizontal bar) extending over the whole map > at a certain latitude range (approx 65 deg. north), whereas > > map('world',pro='rectangular',para=180) > > (which should be the same) does not show the artifact. > > the artifact shows up in other projections as well, e.g. > > map('world',pro='bonne',para=45) > > > which seems to show that the problem might be in the data base of the > map (i.e. polygon definition)?? > > > any ideas? >The short answer is RTFM, and now that I have again :-), I note that there is a wrap= option. Setting that to TRUE seems to have the desired effect. Ray