Dear Roger, thank you very much again for your help. I didn't know about PBSmapping and the Rgshhs() function. It seems both will be very useful to me.
Thanks again, Fernando Mayer. Roger Bivand escreveu: > On Mon, 12 Feb 2007, Roger Bivand wrote: > >> On Mon, 12 Feb 2007, Fernando Mayer wrote: >> >>> Roger, thanks for your explanations. Thanks also to Edzer Pebesma who >>> provided soma additional improvements. However, now I think I have 2 >>> problems, as follows: >>> >>> Roger Bivand escreveu: >>> >>>> If you comment out the lines: >>>> >>>> # if(missing(map)) stop("map object is missing.") >>>> # if(!inherits(map, "Map")) stop("Map.obj must be of class Map") >>>> # if(missing(variable)) stop("variable to be plot is missing") >>>> >>>> in ProportionalSymbolMap(), and rename the map argument as verts, you can >>>> pass the coordinates in: >>>> >>>> library(maps) >>>> map <- map("county", "illinois", fill=TRUE, col="transparent", plot=FALSE) >>>> library(maptools) >>>> str(map) >>>> ID <- substring(map$names, 10) >>>> ill <- map2SpatialPolygons(map, ID, proj4string=CRS("+proj=longlat")) >>>> plot(ill, axes=TRUE) >>>> x <- runif(102) >>>> ProportionalSymbolMap_rev(coordinates(ill), x, max.size=0.3) >>> # Problem 1 >>> >>> Doing exactly this, I have an error in >>> >>> > plot(ill, axes=TRUE) >>> Error in as.vector(x, "double") : cannot coerce to vector >>> >>> and I was not able to find out what is going wrong. However if I do >>> >>> > map("county", "illinois", fill=TRUE, col="transparent", plot=T) >>> >>> before all that code code and ignore the error, I can see the map with >>> the proportional symbols. So I don't know exactly how long this error >>> influence on what was to be the point here. But, I understood >>> something new here and know comes the >> At a distance it's difficult to say - but from #2 below, it doesn't >> matter, because the map is only a background, it does nothing itself. >> >>> # Problem 2 >>> >>> As far as I could understand, the polygon IDs are used to identify >>> where the symbols are to be plotted (after the processment with >>> map2SpatialPolygons()). Maybe it was my mistake haven't said this >>> before, but what I'm trying to do is to plot the symbols not in the >>> land, but in the ocean. So I think there's no polygon IDs in this case >>> isn't? >> Well, using map() to access boundary data is usually to attach data to the >> polygons, but your case is different, you only need a background. My first >> idea would be to see whether the PBSmapping package already has what you >> need - they are Northern Pacific, but that doesn't have to hurt for your >> South Atlantic location. >> >> I think that I would try to get the coastlines you need from map() or >> Rgshhs() in maptools (possibly with a higher resolution GSHHS database), >> and convert them to a PBSmapping object. The reason for suggesting >> PBSmapping is that the functions provided there are for fisheries >> research, and so may be closer to you than more general functions. >> >> library(maptools) >> gshhs.c.b <- system.file("share/gshhs_c.b", package="maptools") >> SA <- Rgshhs(gshhs.c.b, xlim=c(295,340), ylim=c(-10,-55))$SP > > Of course: > > SA <- Rgshhs(gshhs.c.b, xlim=c(295,340), ylim=c(-55, -10))$SP > > Sorry! > >> plot(SA, axes=TRUE, col="grey") >> SA_PBS <- SpatialPolygons2PolySet(SA) >> plotMap(SA_PBS) >> >> I found the map on page 19 of their User Guide quite like what you are >> after, but they choose to colour-fill the quadrats. >> >> The same things can be done with generic sp class objects too. >> >> Roger >> >>> What I'm trying to do exactly is maps to plot fishery data, with the >>> symbols proportional to catch, effort, etc. I was trying something >>> like this [1], which is a function using map(), degAxis(), quantile(), >>> points(), legend(), etc. However I would like to improve this, mainly >>> the legend and the way the symbols are plotted. That's why I was >>> trying the ProportionalSymbolMap(). But now, because of the polygon >>> IDs I'm not sure anymore how this could be done. >>> >>> [1] http://img468.imageshack.us/img468/9397/rplot005us9.png >>> >>> Thanks again for the explanations, >>> >> > -- Fernando Mayer Grupo de Estudos Pesqueiros - GEP Centro de Ciências Tecnológicas, da Terra e do Mar - CTTMar Universidade do Vale do Itajaí - UNIVALI Itajaí - SC - Brasil e-mail: fernandomayer [EMAIL PROTECTED] gmail.com _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo